diff --git a/ChangeLog b/ChangeLog
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,1924 +1,1928 @@
 2019-04-29  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix Python3 StringIO import compatibility -- thanks to Tom Neep for the patch!
 
 2019-03-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add -m/-M filtering to yodadiff.
 
 2019-02-27  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix HistoBin2D printing in Python interface.
 
+2019-02-17  Jon Butterworth  <j.butterworth@ucl.ac.uk>
+
+	* Protect yodamerge against zero-valued (?!) ScaledBy attributes.
+
 2018-12-10  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Release 1.7.4
 
 2018-11-16 Christian Gutschow <chris.g@cern.ch>
 
 	* Roll out sameBinning methods for Profile1D and Profile2D.
 
 2018-11-08 Christian Gutschow <chris.g@cern.ch>
 
 	* Add sameBinning methods for Histo1D and Histo2D.
 
 2018-11-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Remove debug couts from single-AO Writer::write() function.
 
 	* Add --ignore-missing and --ignore-new flags to yodadiff.
 
 	* Tidy up point-comparison output of yodadiff.
 
 2018-10-13 Christian Gutschow <chris.g@cern.ch>
 
 	* Fix additional weighting in yodamerge
 
 2018-09-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Release 1.7.3
 
 2018-09-12 Louie Corpe  <lcorpe@cern.ch>
 
 	* Fix bug in multi-err point reader which was not parsing Variations correctly,
 	and a minor typo where the err- was duplicated for the additional columns.
 
 2018-09-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix missing y and z components of Point2D and Point3D equality testing.
 
 2018-09-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add array accessors of x,y,zMins/Mids/Maxs/Vals/Errs, etc. to
 	Python Histo2D and Profile2D.
 
 2018-08-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Update embedded yaml-cpp to v0.6.0.
 
 	* Convert xyzMin/Max properties to functions in the Python interfaces.
 
 	* Return numpy arrays if possible in Python interface array methods.
 
 2018-08-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Release 1.7.2
 
 	* Add missing bin(i) method to Python Profile1D interface.
 
 2018-08-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Avoid const-overloading clash for binAt functions.
 
 2018-08-14  Chris Gutschow  <chris.g@cern.ch>
 
 	* Merge Graeme Watt's modifications to yodadiff.
 
 2018-08-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Release 1.7.1
 
 2018-08-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* yodadiff now supports quiet (-q) and list (-l) modes.
 
 2018-06-01  Louie Corpe  <lcorpe@cern.ch>
 
 	* Point1,2,3D now support multiple error sources for the highest dimension.
 
 	* Scatter1,2,3D now read in/out with additional columns for the extra error
 	sources, with a variations() method to check with sources are available
 
 2018-05-02  Andy Buckley  <andy.buckley@cern.ch>
 
 	* StringUtils.h: Replace std::ptr_fun (removed in C++17) with a lambda function. Thanks to Stefan Richter.
 
 2018-04-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add "-" = stdin/stdout recognition to C++ IO functions.
 
 	* Convert remaining Python read/write methods to use the C++ IO functions.
 
 	* Convert Python read/write methods with filename arguments to use the gzip-aware IO functions.
 
 2018-04-27  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix missing lock=false flag initialisation in Histo2D constructor from a Bins vector.
 
 	* Improve axis locking error messages.
 
 2017-12-21  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.7.0 release
 
 2017-12-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add Nentries printout to yodals -v
 
 2017-09-18  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Patches for ROOT conversion from Robert Hatcher -- thanks!
 
 2017-09-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add YODA format version annotation, at version 2, and update
 	YODA reader to use version info and multiline YAML EOF marker.
 
 	* Write YODA annotations in YAML with a --- YAML break-line.
 
 2017-09-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Enable compressed writing from Python.
 
 2017-09-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Remove UNUSED macro in favour of anonymous args.
 
 	* Enable zipped writing... but only works from C++ so far.
 
 2017-09-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add HistoBin2D::area(), and provide a default normto=1.0
 	argument on the Python Histo2D.normalize() method.
 
 2017-09-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Change license explicitly to GPLv3, cf. MCnet3 agreement.
 
 	* Parse YODA format AO headers as YAML (restriction to single-line dict entries for now).
 
 2017-08-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Use a slightly enhanced fast numeric parser in ReaderYODA (taken
 	from LHAPDF, originally inspired by Gavin Salam).
 
 	* Add an UNSCALE spec option to yodascale, to undo ScaledBy effects.
 
 2017-08-19  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add optional zlib support via zstr -- massive thanks to Dmitry
 	Kalinkin for the lovely patch!
 
 2017-08-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix setVal(i, x) numbered-axis methods on Point2D and Point3D:
 	switch break statements were missing.
 
 	* Explicitly load all ROOT objects as a list rather than
 	generator. Patch from Dmitry Kalinkin.
 
 2017-07-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improvements to yodaplot, including two operating modes: the
 	default CMP mode is suitable for plotting histos by path, from raw
 	.yoda files.
 
 	* Update yoda.plotting functions to treat plot-keys as args and AO
 	annotations via case-insensitive keys.
 
 	* Add annotationsDict to the Python AO interface.
 
 	* Add AO as an alias for AnalysisObject.
 
 2017-07-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add parallel/compatibility yoda1 package to aid eventual transition to YODA v2.
 
 2017-07-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add x,y,zMins and Maxs to all 1D data types and scatters (and
 	x,yMin/Max to the scatters) -- Python interface only.
 
 	* Rework some of the yoda.plotting tools, making it a bit more
 	compatible with user-scripted matplotlib.
 
 2017-07-18  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add convenience aliases H1D, H2D, P1D, P2D, and S1D, S2D, S3D
 	for the HistoXD, ProfileXD, and ScatterXD classes respectively.
 
 2017-07-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add xyVals/Errs and other 'bin array property' accessors to the
 	Python Histo1D and Profile1D types: important for connection to
 	matplotlib.
 
 2017-06-28  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Use Python natsort library to sort yodals output if available.
 
 2017-06-18  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.6.7 release.
 
 2017-05-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* pyext/yoda/rootcompat.pyx: Fix ordering of TH1 vs. TProfile
 	conversion -- TProfile *is* a TH1, so we have to test for the more
 	specific type-match first. Thanks to Dmitry Kalinkin for the
 	patch.
 
 2017-05-02  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add static Reader methods to match the Writer ones.
 
 2017-02-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix Histo2D and Profile2D total distribution reading from YODA format.
 
 2017-02-19  Holger Schulz <holger.schulz@durham.ac.uk>
 
 	* Convert TH1F to TH1D in root2flat. Much simpler than duplicating
         the TH1D stuff in pyext.
 
 2016-12-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.6.6 release.
 
 2016-12-12  Holger Schulz <holger.schulz@durham.ac.uk>
 
 	* Bugfixes in Cython bins accessors for Histo2D.
 
 2016-11-17  Leif Lonnblad <leif.lonnblad@thep.lu.se>
 
 	* Fixed warning messages about the obsoleteness of AIDA so that the scripts actually still work.
 
 2016-09-28  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.6.5 release, for the benefit of ROOT fans.
 
 	* Fix handling of --enable/disable-root configure options.
 
 2016-09-26  David Grellscheid  <david.grellscheid@durham.ac.uk>
 
 	* Improvements to Cython version testing.
 
 2016-09-25  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.6.4 release.
 
 2016-09-20  David Grellscheid  <david.grellscheid@durham.ac.uk>
 
 	* Remove aliases for @property functions. They were scheduled for
 	removal anyway, and don't work with Cython >= 24.
 
 2016-09-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Update configure scripts to use newer (Py3-safe) Python testing
 	macros.
 
 2016-08-09  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.6.3 release!
 
 2016-07-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add 'add' modes for scatter combination to yodamerge.
 
 	* Fix yodamerge scatter averaging to use the first AO.
 
 2016-07-21  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add --type-mismatch-mode flag and fallback logic to yodamerge.
 
 	* Fix yodamerge logic to handle cases where an AO only appears once.
 
 2016-07-19  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Deprecate flat2yoda script and add warning output to it and the AIDA conversion scripts.
 
 	* Add a convenience yoda2yoda script.
 
 2016-07-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Try to build PyROOT interface by default, if root-config is found.
 
 2016-07-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Remove accidentally remaining reference to Boost flags in yoda-config.
 
 2016-07-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.6.2 release!
 
 2016-07-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Pass the toNewScatter3D() scalebyarea flag to the called toScatter3D() functions.
 
 2016-06-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Re-enable the disabled-for-some-reason Scatter1D combineWith Python mappings.
 
 2016-04-28  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.6.1 release!
 
 	* Add a unit test for annotation handling correctness.
 
 	* Fix numerical precision of string storage of floating-point attributes.
 
 	* Fix a bug in use of the replacement for lexical_cast.
 
 2016-04-20  Andy Buckley  <andy.buckley@cern.ch>
 
 
 	* Version 1.6.0 release!
 
 2016-04-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Extend SFINAE craziness to allow writing of any object
 	(e.g. smart pointer) that can be dereferenced to something that
 	has AnalysisObject as its base class... and also to any container
 	of them! Amazing what you can do with C++11!
 
 2016-04-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add a few consts to the arguments in Scatter error setting via pairs.
 
 	* Fix double-writing of minus errors in WriterYODA for Scatter1D
 	and Scatter3D. Thanks to Graeme Watt for the report and fix.
 
 2016-04-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Remove Boost dependency and require C++11 compilation.
 
 2016-04-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add a --guess-prefix flag to yoda-config, cf. fastjet-config.
 
 2015-12-20  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Change AO uncomputable division and mkScatter operations to
 	return/set NaN rather than 0 -- behaviour change requires new
 	major version series 1.6.
 
 2016-03-09  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.9! (oh no, we're out of convenient version number space!!)
 
 2016-03-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add abs function to eq calculation in yodadiff.
 
 2016-02-29  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Remove blocking of builds against ROOT6 -- it works fine.
 
 2016-02-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add a --add option to yodamerge, for simple histo
 	stacking. Thanks to Chris Gutschow for the patch, although my
 	spidey sense is tingling...
 
 2015-12-21  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.8!
 
 	* Add a rebinning unit test, pytest-rebin.
 
 	* Add optional range arguments to rebinBy methods, allowing block
 	rebinnings to be applied only within a range of (original) bin
 	indices.
 
 	* Add missing root.py submodule file. Oops!
 
 2015-12-20  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Convert linspace to use multiplication rather than repeated
 	addition to construct edge values, reducing precision errors.
 	Thanks to Holger Schulz for the suggestion.
 
 2015-12-15  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add xEdges() methods to Axis1D and the Histo1D and Profile1D
 	that use it. The returned edge lists are finite only, i.e. they do
 	not contain the +-inf values on the ends of the internal
 	BinSearcher edges.
 
 2015-12-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.7!
 
 	* Extend batch-adding in ReaderYODA to include Scatter types.
 
 	* Add a match_aos function to Python, for filtering AO lists/dicts
 	on path patterns and anti-patterns.
 
 2015-12-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add a flag to yoda2root to change whether the conversion is to
 	'proper' types or to (more robustly) TGraphAsymmErrors objects.
 
 	* Fix accidental use of S2D_MODE flag where S1D_MODE should have
 	been used, in yodamerge. Thanks again to Radek Podskubka.
 
 	* Allow new rebinTo() merging to restrict to a subset of the bin
 	range, merging the outside bins into the overflow distributions.
 
 2015-12-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add a rebinTo() method on Axis1D, allowing rebinning to a new
 	given set of bin edges. Add an explicitly named rebinBy(), and
 	overloaded rebin() aliases for both, and pass through to Histo1D
 	and Profile1D APIs. Plus other internal tweaks to binning
 	functionality... anticipating/fuelling the fundamental rewrite.
 
 2015-12-10  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improve ReaderYODA to use temporary bin containers, to minimise
 	calling sort when adding bins to histos. A quick test suggests
 	this has sped up big file reading by a factor of 30 or so!!!
 
 	* Add missing addBins() operators (only in C++ so far) to Histo
 	and Profile classes.
 
 	* Fix Counter::numEntries to return an unsigned long rather than double.
 	Thanks to Radek Podskubka for the bug discovery and detective work.
 
 	* Improve sortedvector to insert new elements into the sorted
 	position, rather than resorting the whole vector. This should be a
 	bit more efficient, but I think the asymptotic complexity is the
 	same. Might help a bit with reading big data files.
 
 2015-12-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add yoda.HAS_ROOT_SUPPORT flag, for API user convenience.
 
 2015-11-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.6!
 
 	* Make AO path setting and retrieval prepend a leading slash if it
 	is missing (unless the path is completely empty).
 
 2015-11-21  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add root2yoda conversion script.
 
 	* Deprecating yoda.to_root() in favour of yoda.root module, which
 	contains to_root and to_yoda functions, as well as a ROOT file
 	walking function.
 
 2015-11-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Map ROOT-to-YODA (as scatter) functions to Python. Phew.
 
 	* Map new to-ROOT functions, including TGraph ones, to Python.
 
 2015-11-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* ROOTCnv.h: Add toScatter3D ROOT->YODA, and toNew* YODA->ROOT
 	conversion routines.
 
 	* ROOTCnv.h: Fix bug in toTH2D(const Histo2D& h) as used with
 	ROOT6. Thanks to Tim Martin.
 
 2015-11-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix double-dealloc in new Point class hierarchy Python mapping.
 
 2015-10-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Make the version() function inline, and the numerical constants static.
 
 	* Change the default plotting backend to MPL rather than the much slower PGF.
 
 2015-10-09  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Reinstate __getitem__  special methods for Scatters in Python.
 
 	* Provide dim() methods/attributes for the Point and Bin base classes.
 
 	* Rename set*Err to set*Errs for the asymmetric variants. Plural
 	aliases are also provided for the symm case.
 
 2015-10-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Pass std::pairs by reference in Point*D error setting functions.
 
 	* Add Point base class with generic accessors to Point*D
 	properties via an integer axis ID argument.
 
 2015-10-07  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.5 release.
 
 	* Counter.pyx: Typo fix in sumW mapping.
 
 	* yodamerge: Re-add checking for non-emptiness before merging, in
 	case the empty ones are missing a ScaledBy attribute. Won't
 	normally apply to Profiles, since they don't usually get
 	normalised, but we might as well include them in the vetoing since
 	empty histos don't contribute to the merging. Added a command-line
 	option to disable this heuristic since in very strange situations
 	a null sumW does not mean no fills.
 
 2015-10-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.4 release.
 
 	* ReaderYODA: Typo fixes in Counter filling of sumW and Scatter3D reader state flag.
 
 	* yodamerge: add merging heuristics for Scatter1D and Scatter3D (needs unification)
 
 2015-10-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* yodamerge: add a fix for empty-in-all-runs histo merging; thanks
 	to Daniel Rauch.
 
 2015-10-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding dim() function and corresponding Python attribute to AnalysisObject.
 
 	* Map Counter arithmetic operations into Python.
 
 	* Map Counter mkScatter() into Python (as bound method).
 
 	* Add a YODA::version() function, mapped into Python and used to
 	set the yoda.__version__ variable.
 
 2015-10-01  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Expose the yoda.plot() Python function in a way that doesn't
 	automatically induce a dependence on matplotlib.
 
 2015-09-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix yodals to work with Counters.
 
 2015-09-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.3 release.
 
 	* Update Boost version requirement to 1.48, due to use of
 	type_traits/has_dereference, and add a check for that feature's
 	header.
 
 2015-09-19  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Further improvements to handling leading _multiple_ # marks on
 	YODA format BEGIN lines.
 
 2015-09-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.2 release.
 
 	* Tolerate leading # symbols without separating whitespace on
 	BEGIN lines in YODA format parsing.
 
 	* Further improvements to handling LowStatsErrors in YODA format writing.
 
 	* Fix shadowed variables that made ReaderYODA unhappy.
 
 2015-09-03  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.1 release.
 
 	* Fix bugs in Python wrapper for Point3D.
 
 2015-08-28  Peter Richardson  <Peter.Richardson@durham.ac.uk>
 
 	* Catch LowStatsError when writing multiple histograms so only the
 	histogram with the problem is not written
 
 2015-08-28  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.5.0 release.
 
 2015-08-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improve protection of efficiency calculation against the weird
 	world of general weighted events.
 
 2015-08-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add some protection against calling matplotlib's legend() method
 	if there are no valid labels to display, to suppress an MPL
 	warning message when using yoda.plot().
 
 2015-08-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix cut & paste typo, and add LowStatsError catching in Profile division.
 
 2015-08-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Replace old Spirit-based ReaderYODA with the new hand-rolled one.
 
 	* Adding filling of Histo1D, Profile1D, Histo2D and Profile2D in
 	new ReaderYODA. More hacking of Axis and Histo/Profile
 	interfaces... needs clean-up, and infinite binning implementation.
 
 2015-08-07  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Convert the ReaderFLAT parser to also use a simple hand-written parser rather than Spirit.
 
 2015-08-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add methods for Counter, Axis and Histo1D internal state
 	access/setting, mainly for new persistency. NEEDS PRE-RELEASE TESTING!!!
 
 2015-07-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Remove # markers from YODA format BEGIN/END output. The parser
 	will continue to accept them.
 
 2015-07-29  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add SFINAE trait magic to restrict write(RANGE) functions to
 	accepting iterables. Also generalising to allow either
 	container-of-objects or container-of-pointers args by providing a
 	writeBody(AO*) function to complement writeBody(AO&). Based on a
 	patch from Lukas Heinrich.
 
 	* Add configuration of output streams to throw exceptions on
 	bad/fail state (based on patch from Lukas Heinrich).
 
 2015-07-01  Andy Buckley  <andy.buckley@cern.ch>
 
 	* 1.4.0 release.
 
 2015-06-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* More tweaks to yodamerge: adding control of S2D merging
 	strategy, and now performing weighted normalized histo merges
 	without reference to an absolute normalization.
 
 	* Change yodamerge norm-detection heuristic to just look for a
 	ScaledBy attribute rather than fuzzily compare norms.
 
 2015-06-26  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Removing add, subtract, and divide functions and operators on
 	Scatter types, and re-implementing Histo and Profile divide
 	functions explicitly rather than via mkScatter. Also removed from
 	the Python interface. The combine() methods remain.
 
 2015-06-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding workaround versions of binAt to all the Python histo
 	types (for some reason the direct mapping that works for bin(i)
 	produces a compile error for binAt(x) :-/
 
 2015-06-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Renaming, tidying, completing, etc. the Python-mapped methods on Bin1D and Bin2D.
 
 	* Rename Python Histo2D mean, variance, etc. pair-returning
 	methods to xyMean, xyVariance, etc., to distinguish from Profile2D
 	mean, variance, etc.
 
 	* Add Python mappings of all the methods below.
 
 	* Add full set of {x,y}{Mean,Variance,StdDev,StdErr,RMS} to 1D and
 	2D binned distributions.
 
 	* Add optional includeoverflows=True argument to all binned AO
 	numEntries and effNumEntries.
 
 	* Fix type of numEntries to always be unsigned long.
 
 2015-06-18  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix typos in Point3D Python mapping (accidentally trying to get
 	the ptr via _Point2D rather than _Point3D).
 
 2015-06-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding an AnalysisObject::name() method, to return the last part
 	of the path. Mapped into a Python property.
 
 	* Adding an optional usestddev argument to mkScatter for profile
 	types, so the error bars can represent distribution width rather
 	than uncertainty on the mean. Mapped to Python.
 
 2015-06-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding unpatterns arguments to Python read functions, and
 	auto-conversion from single strings and re.compile()d strs.
 
 2015-06-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add binAt(x,y) and binIndexAt(iglobal) Python methods for 2D
 	histos. Still want a way to get and pass a pair of bin indices, I
 	think.
 
 	* Adding includeoverflows optional args for Histo1D (eff)numEntries.
 
 	* Adding Rename Histo1D integral() methods as integral(),
 	integralRange(), and integralTo(), and mapping to Python.
 
 2015-06-02  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding missing binAt and binIndexAt methods to Histo1D and
 	Profile1D, plus other minor Python mapping tweaks.
 
 	* Add a regex pattern match optional argument to the IO.read()
 	Python functions, for pre-emptive filtering.
 
 2015-03-27  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix a harmless possibility to raise an FPE exception in the
 	BinSearcher. Thanks to Leif Lonnblad for the discovery, debug and
 	patch!
 
 2015-03-19  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Bump version for 1.3.1 release.
 
 2015-03-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding usefocus optional argument to some mkScatter functions, plus the Python bindings.
 
 	* Cleaning up some Python mappings of 2D histogram bin classes.
 
 	* Removing mappings of bin-level fill and scale operations in Python.
 
 	* Fix formatting and error handling in Python Bin and Dbn __repr__ methods.
 
 	* Add a -i/--in-place option pair on yodascale.
 
 2015-02-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Convert script matching options to use re search rather than match.
 
 	* Adding matching options and verbose option to yodals.
 
 2015-01-27  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improvements and additions to ROOTCnv.h routines, particularly
 	to TProfile creation: thanks to Roman Lysak for advice.
 
 2015-01-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add convenience YODA/YODA.h header.
 
 2015-01-15  Andy Buckley  <andy.buckley@cern.ch>
 
 	* yodascale now uses PointMatcher and can normalize or multiply to
 	abs values or ref histos/bin ranges.
 
 2015-01-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding yoda.matcher Python sub-package with PointMatcher
 	functionality. To be used in Professor 2.0 and in yodascale.
 
 	* Adding 'scat2' type to yodahist.
 
 	* Add match/unmatch args to all conversion scripts, via a new Python yoda.script_helpers function.
 
 	* Script updates, improved docstrings, and improved tab completion.
 
 2014-12-10  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add a yoda.plotting sub-module, based on matplotlib.
 
 2014-12-03  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Small build improvements: cleaning test1.root from the yoda2root
 	test, and adding a make target & flag file for mktemplates in
 	pyext/yoda to make sure that it only gets run once.
 
 2014-11-25  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Handle overflow filling in binned types without invoking an exception.
 
 	* Change inRange to have non-fuzzy comparison behaviour.
 
 2014-11-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improving/adding __div__ functions in Python for all binned types.
 
 	* Add std:: prefix to isinf() calls in BinSearcher.h.
 2014-09-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* 1.3.0 release!
 
 	* Use numEntries() rather than effNumEntries() when checking
 	consistency of inputs to efficiency() calculations -- the
 	effNumEntries of a set can be smaller than that of a strict
 	subset, surprisingly!
 
 2014-09-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Small improvements to yodahist and yodaplot behaviours/UIs.
 
 	* Adding setX/Y/Z(val, err) methods to Point3D.
 
 	* Add an efficiency method for 2D histos.
 
 	* Hide fill and fillBin methods from Python mappings of bin types.
 
 2014-09-01  Andy Buckley  <andy.buckley@cern.ch>
 
 	* YODA 1.2.1 release!
 
 2014-08-29  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Hide non-const access to bin objects from histogram users:
 	avoids potential for inconsistency between total dbns and in-range
 	bins.
 
 	* Bug in BinSearcher fixed by Peter Richardson: constructor
 	arguments were passed in the wrong order when constructing a
 	LinEstimator in cases where log binning wouldn't be allowed.
 
 2014-08-26  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add protection against / characters in histo names in yoda2root
 	(thanks to Will Bell for the report and suggested patch).
 
 2014-08-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add +=, -=, *-, /=, ++ and -- operators to Counter, along with
 	an (implicit) constructor from a double -- all for user
 	convenience so Counter can be used in lieu of a simple number.
 
 2014-08-15  Andy Buckley  <andy.buckley@cern.ch>
 
 	* YODA 1.2.0 release!
 
 	* Permit +-inf values to be filled into histograms; NaN fills will
 	still explicitly throw an exception.
 
 	* Add unit tests for Counter, Scatter1D, and Scatter2D, including
 	persistency.
 
 	* Adding YODA and FLAT format I/O for Scatter1D and Counter (as
 	far as currently possible -- FLAT Counter can't be read due to a
 	#item ambiguity, just like the one between the YODA format Point3D
 	and ProfileBin1D). To be continued...
 
 2014-08-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Python mappings for Dbn0D and Counter, and other improvements.
 
 	* Adding val() and err() methods to Counter, and errW() and
 	relErrW() to all DbnXD types.
 
 	* Adding Scatter1D and Point1D types, with conversion from Counter
 	supported. Both Counter and Scatter1D still need to be supported
 	by YODA persistency.
 
 2014-08-11  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add ROOT version checking to configure. Thanks to Michael Grosse
 	for the report/request.
 
 2014-08-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Remove all methods not specific about the axis to which they
 	refer, e.g. Histo1D::mean -> xMean. Also remove all related
 	aliases (a nightmare to maintain) and low/highEdge and midpoint
 	functions: use the proper xMin/Max/Mid from now on. This is a
 	significant compatibility breaking API change (and the decision
 	was not taken lightly) so will require a 2nd digit version change.
 
 	* Lots of adding xMin/Max etc. functions to C++ and Python bin/histo classes.
 
 	* Compiler pickiness fixes in BinSearcher.
 
 	* Improvement to linspace, avoiding fuzzyEquals and again making
 	sure that the end value is exact.
 
 2014-07-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix to logspace: make sure that start and end values are exact,
 	not the result of exp(log(x)).
 
 	* Clean-up, minor improvements, and adding a test for BinSearcher and friends.
 
 2014-07-19  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Various consistency improvements and minor bugfixes to Python
 	mapping utils and Dbn and Bin objects.
 
 	* Fix Axis2D::reset, which was resetting the total dbn and
 	outflows, but not the bins!!! Thanks to Ewen Gillies for the
 	report.
 
 2014-07-18  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add scaleX,Y,Z and scaleXYZ to Point and Scatter classes, and
 	deprecate less explicit/consistent Scatter2D/3D.scale method.
 
 2014-07-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* yodascale now writes out rescaled histograms and profiles rather than scatters.
 
 	* A few more improvements on Point2D/3D, adding x,y,zMin/Max function mappings.
 
 	* Add first version of a yodascale script, based on code from Simone Amoroso.
 
 2014-07-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* More Scatter and 2D histo interface improvement.
 
 	* Remove 'return *this' from Scatter2D/3D add and combine methods.
 
 	* Add unit test checks for 1D and 2D mkScatter functions.
 
 	* Improve Scatter2D/3D C++ and Python interfaces.
 
 	* Add Scatter3D Python mapping.
 
 2014-07-15  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add auto-parsing of yes/no/on/off/true/false as bools in the
 	Python ao.annotation() function.
 
 	* Add parsing of yodaplot styles from command line args and
 	analysis object annotations.
 
 2014-07-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix infinite recursions in Python wrappers for Point2D and
 	Point3D, and make the Python Point3D interface more standard.
 
 	* Add yodaplot script for basic plotting, using pgfplots as a backend.
 
 2014-07-10  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add mkScatter(Scatter2D) and mkScatter(Scatter3D) functions and
 	Python mappings: this allows all AOs to be used as args to
 	mkScatter(...) without needing to check if they already are
 	scatters.
 
 2014-07-02  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Set y value and/or error to 0 in mkScatter(Histo1D) if an
 	exception is thrown when calculating the appropriate values. Need
 	an optional param to control this error handling behaviour between
 	set-zero and skip-bin?
 
 2014-07-01  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add exception translation to the mkScatter functions.
 
 	* Add -m/-M match/unmatch options to yodacnv -- useful for
 	filtering histogram file contents in a YODA->YODA conversion.
 
 2014-06-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Don't complain about merge assumptions if there is only one
 	object with that path name to be 'merged'
 
 2014-06-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding explicit int cast in Python wrapping of numEntries functions.
 
 2014-06-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding yodals script to list data file contents.
 
 2014-06-11  David Grellscheid  <David.Grellscheid@durham.ac.uk>
 
 	* pyext/yoda/Makefile.am: 'make distcheck' and out-of-source
 	builds should work now.
 
 2014-06-10  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix use of the install command for bash completion installation on Macs.
 
 2014-06-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* YODA 1.1.0 release. Middle version number change to reflect API changes w.r.t 1.0.6.
 
 	* Adding unit tests against ref data for yodamerge in make check.
 
 2014-06-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix silly typos in yodamerge which somehow made it past "make check" testing :-(
 
 2014-06-02  Andy Buckley  <andy.buckley@cern.ch>
 
 	* YODA 1.0.7 release. DO NOT USE: prefer 1.1.0, above.
 
 2014-05-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Removing 'foreach' macro definition and using raw BOOST_FOREACH instead until C++11 is allowed.
 
 	* Adding pytest-p1d and pytest-p2d tests, and FLAT writing/reading in pytests.
 
 	* Tweaking WriterFLAT and adding ReaderFLAT functionality for 2D histos and profiles.
 
 2014-05-30  Holger Schulz  <hschulz@physik.hu-berlin.de>
 
         * Some basic (FLAT) write-out capability for 2D histos
 
 2014-05-29  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improvements to the yodahist script, including support for 2D
 	histograms and input files.
 
 	* Adding bin edges constructors for all 1D and 2D histos in Python.
 
 2014-05-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improvements to Profile2D and Point2D interfaces in Python.
 
 	* Add a single-file at a time yodacnv multi-format converter
 	script (thanks to Andrii Verbytskyi for the suggestion).
 
 2014-05-19  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Typo fixes in Profile2D YODA-format parsing: 2D histo tests now pass!
 
 	* Adding Python tests for Histo2D and Profile2D.
 
 	* Adding a YODA/Predicates.h header and using it in Axis2D bin edge construction.
 
 	* Enabling Profile2D writing in various Writers, and a bit of IO code tidying.
 
 2014-05-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Disable writing out of Histo2D and Profile2D outflows for now,
 	while they are redesigned, and get 2D I/O working for the in-range
 	part.
 
 2014-05-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Mapping the divide and efficiency functions into the Python
 	interface as class methods, including the __div__ special
 	function.
 
 2014-05-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add the AnalysisObject::type() method back in Python (even
 	though type(ao) is more Pythonic, this may be useful)
 
 2014-05-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add Profile2D YODA format writing, note need for Scatter format
 	change, add sumXY storage to both 2D histo types.
 
 2014-05-03  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding YODA reader functionality for Histo2D and Profile2D, but
 	without outflows support yet.
 
 2014-04-25  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding simple command line yodahist script for quick 1D
 	histogramming from plain text files, with weight support. More
 	development to come!
 
 	* Mapping linspace, logspace and a few stat functions into Python.
 
 2014-04-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fixes, script installation, and detailed numerical comparisons
 	in yodadiff.
 
 2014-04-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Change AnalysisObject::annotations to return the list of
 	annotation keys rather than the map, since the previous behaviour
 	mapped very badly into Python.
 
 2014-04-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add special case handling for 2-arg use of x2y scripts where the
 	second arg is -, for stdin. This will be treated as writing out to
 	stdout, not converting two files one of which is stdin.
 
 2014-04-15  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding a more portable version of getline to be used in the YODA
 	file parsing to avoid falling over on DOS-produced input files.
 
 2014-04-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding the namespace protection workaround for Boost described
 	at http://www.boost.org/doc/libs/1_55_0/doc/html/foreach.html
 
 2014-04-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding an assumed-equal-run-size, ratio-like merging heuristic
 	for Scatter2Ds to yodamerge, and renaming the --normalize-all flag
 	to --assume-normalized.
 
 	* Adding and installing a pkg-config data file for YODA.
 
 	* Rationalising (and fixing?) the yodamerge logic re. user &
 	normalization scalings, and making way for a Scatter2D merging
 	heuristic.
 
 2014-03-10  Andy Buckley  <andy.buckley@cern.ch>
 
 	* YODA 1.0.6 release.
 
 2014-03-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improvements to AnalysisObject annotation handling in Python.
 
 	* Adding rescaling arguments to yodamerge (and scale function to Python Scatter2D).
 
 	* Better documentation and consistency of Histo and Profile Python
 	wrappers, and removing some inappropriate attributes.
 
 	* Adding clone() and newclone() functions to all analysis object classes.
 
 2014-02-28  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Cython mapping improvements, esp. adding numPoints/numBins
 	functions and better Scatter2D __repr__.
 
 	* Adding mapping of the mkScatter functions into Python (as
 	methods on Histo1D and Profile1D rather than the original free
 	functions, at least for now: some Python type-identifying
 	boilerplate is needed to make a single mkScatter function work in
 	Python)
 
 2014-02-27  Leif Lönnblad  <Leif.Lonnblad@thep.lu.se>
 
 	* Minor modifications to BinSearcher to avoid NaN's. The NaN's
 	were treated correctly before, but better to avoid them all
 	together.
 
 2014-02-27  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding the generated pyext/yoda/rootcompat.cpp to the tarball
 	and sorting out the ROOT/Cython interface conditionals a bit more
 	sanely. Thanks to Oldrich Kepka for the bug report.
 
 	* Protecting yodamerge against input histograms with zero
 	integrals (thanks to Christian Bierlich for the bug report).
 
 2014-02-14  Frank Siegert  <frank.siegert@cern.ch>
 
 	* Fix race condition with mktemplates.
 
 2014-02-12  David Grellscheid  <david.grellscheid@dur.ac.uk>
 
 	* Fix bug in mktemplates code (thanks to Christian Johnson for the bug report).
 
 2014-02-09  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding explicit include/generated dir creation to Python
 	extension build (thanks to Christian Johnson for the bug report).
 
 2014-02-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* 1.0.5 release!
 
 2014-02-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding patches to ReaderFLAT and ReaderYODA use of Boost Spirit
 	which reduce the Boost version requirement from 1.47 ->
 	1.41. Thanks to Andrii Verbytskyi for the patch.
 
 	* Protect against invalid prefix value if the --prefix configure option is unused.
 
 2014-02-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding copy assignment operators where missing, based on an
 	implementation in AnalysisObject which only copies rvalue paths
 	and titles if they are non-null.
 
 2014-02-03  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improving (i.e. increasing) bin edge overlap tolerance: 1e-10 relative was too tight.
 
 2014-01-31  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding x/yMid etc. methods on Bin1D and 2D, and more related Python API improvements.
 
 2014-01-28  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding missing fillBin methods to 1D and 2D Histo/Profile Python classes.
 
 	* Fixed yodamerge default output file name treatment.
 
 	* Avoid computing an unrecoverable error in Histo1D.__repr__
 
 	* Clean-ups and API improvements in Python IO functions.
 
 	* Adding more sumW,W2 and (eff)NumEntries attrs to Python objects.
 
 2013-12-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improved argument handling for x2y scripts.
 
 2013-11-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fix to build the Cython rootcompt extension .cpp on request.
 
 2013-11-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding flags for the C++11 or C++0x standard if supported, cf. Rivet.
 
 2013-10-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* YODA 1.0.4 release.
 
 	* Supporting zsh completion via bash completion compatibility.
 
 2013-10-21  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Removing unused internal iterator typedefs from Writer functions.
 
 2013-10-18  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding a yodaenv.sh sourceable script to help with environment setup.
 
 	* Remove Scatters from being handled by yodamerge by blocking the
 	__add__ method fallback.
 
 2013-10-09  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improvements to yoda-config and command-line completion, for the
 	Rivet 2.0.0 release.
 
 2013-10-09  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.0.3 release.
 
 2013-10-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Cython mapping improvements.
 
 	* Adding some improved heuristics and a --normalize-all option to
 	yodamerge. Frank S is now happy again ;-)
 
 2013-10-01  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding operator +, -, +=, -= Python mappings wherever possible
 	for Histo1/2D, Profile1/2D, and Scatter2D.
 
 2013-09-26  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Cython is no longer needed by tarball users.
 
 2013-09-25  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Unset path of returned histogram if those of the args to add()
 	and subtract() are difference.
 
 2013-09-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Python mapping improvements.
 
 2013-09-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Add the -avoid-version flag to libtool.
 
 	* Adding more add and subtract special methods in Python.
 
 2013-09-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* mkScatter schanged to use histo midpoints rather than focuses by
 	default for the point x value.
 
 2013-08-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Version 1.0.2.
 
 	* Some exception message improvements and improving the protection
 	of cosmetic mean calculations in WriterYODA.
 
 2013-07-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding ROOT detection in configure and otherwise updating Dave's
 	rootcompat module so that it'll compile. There might be an
 	inconvenient ROOT version dependency in the signature of one of
 	the PyROOT API functions that is used as a shim :-(
 
 2013-06-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding yoda.m4 from James Robinson.
 
 2013-06-06  Hendrik Hoeth  <hendrik.hoeth@cern.ch>
 
 	* Improve "==" operator in Axis1D and Axis2D
 
 2013-06-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding fillBin() methods to all 1D and 2D histos, and noting
 	that Bin types need a back-link to their axis to maintain
 	consistency.
 
 	* Release of version 1.0.1
 
 2013-06-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Change the divide(Scatter, Scatter) behaviours to use the
 	midpoint of the num/denom bins rather than mean of foci for the
 	output point position (and hence errors, too).
 
 	* Adding a toIntegralEfficiencyHisto function.
 
 	* Adding another Histo1D::integral() function, this time from 0 ->
 	i, maybe including the underflow.
 
 2013-06-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Updating the Cython version requirement to 0.18
 
 2013-06-03  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding relErr functions to 1D and 2D histo and profile bins, and
 	being careful about div by zero.
 
 	* Improvements in error treatment in division (better handling of zeros).
 
 	* Renaming merge-histos to yodamerge and installing it (and
 	improving the usage string a bit).
 
 2013-05-31  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding the Counter type, and ability to output it from the YODA writer.
 
 	* Adding numEntries and effNumEntries methods to 1D and 2D Histo
 	and Profile classes.
 
 	* Adding Dbn0D and using it to implement Dbn1D.
 
 2013-05-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Fixing several nasty errors in argument ordering for
 	Point{1,2,3}D construction in Scatter addPoint functions.
 
 	* Adding abs(...) to the returned Dbn1D::variance(), to avoid
 	problems when negative weights produce negative variance. No, we
 	don't like this either: is there a more correct way?
 
 	* Fixing the efficiency(Histo1D, Histo1D) implementation,
 	cf. http://root.cern.ch/phpBB3/viewtopic.php?t=3753
 
 	* Adding mkScatter(Profile2D)
 
 2013-05-29  Hendrik Hoeth  <hendrik.hoeth@cern.ch>
 
 	* Adding a reader for FLAT files and a flat2yoda converter
 
 2013-05-27  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding a yoda-completion file for bash.
 
 2013-05-17  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Mapping HistoBin1D.relErr in Python.
 
 	* Adding a non-const points() accessor to Scatter2D.
 
 2013-05-13  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding combined value+error setX/Y functions on Point2D.
 
 	* Adding HistoBin1D::relErr()
 
 2013-04-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding Python output handling for single AOs and to be able to
 	use a "-" filename to mean stdout.
 
 2013-04-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Releasing version 1.0.0 -- it seems stable enough.
 
 2013-04-10  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Being more careful about adding -Wno-* flags to the C++ compiler
 	used to built the Cython extension lib.
 
 2013-03-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Removing the use of svn:external to pull in Boost macros and
 	using a minimal local set instead.
 
 	* Using the nice Boost-finding macros from
 	https://github.com/tsuna/boost.m4 and tidying up configure.ac
 
 2013-03-15  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Re-organising the C++ side of the auto-format I/O functions,
 	into a new IO header and separated from the Reader.h and
 	Writer.h. I'm tempted to say that users shouldn't really NEED to
 	ever directly touch the Reader and Writer objects...
 
 	* Adding auto-format read and write functions. I will probably
 	change the API. Python mappings have been provided, but the string
 	workarounds were too much of a pain with Cython 0.16 so I have
 	updated the Cython version requirement to 0.17 where it is
 	automatic and hence much cleaner.
 
 2013-03-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Making the x2y converter scripts write a copy into the *current*
 	directory if only the input is specified.
 
 2013-03-05  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Removing Plot entirely from YODA: it was an anomaly only added
 	to make plot file generation easy, but this is now done better via
 	StringIO (in new compare-histos/rivet-cmphistos).
 
 	* Removing the Plot from Cython... and soon from YODA itself:
 	we'll do this stuff manually and less hackily.
 
 	* Make Cython automatically add a copy of the original call
 	signature to each function's docstring.
 
 2013-03-04  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding Plot mapping to Cython and improving the AO annotations handling in Python.
 
 	* Adding PLOT section writing to WriterFLAT (and WriterYODA,
 	although that might be a bad idea...)
 
 	* Adding aida2yoda and aida2flat converter scripts.
 
 2013-02-02  David Mallows  <dave.mallows@gmail.com>
 
 	* Adding support for Python >= 2.4 (was Python >= 2.6)
 
 	* Fixing miscellaneous warnings on GCC 4.1
 
 2013-01-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding a points() method to the Python Scatter2D wrapper.
 
 	* Adding a virtual destructor to Bin.
 
 2012-12-30  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding support for Boost.Range arguments and file format autodetection in Writer.
 
 2012-11-24  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Bump version to 0.6beta0
 
 	* Adding more ROOT converters. Who knows how to make TProfiles
 	from scratch, but Histo1D and Scatter2D are covered, which should
 	be enough to get started with, at least.
 
 2012-11-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding yoda-config
 
 2012-11-16  Hendrik Hoeth  <hendrik.hoeth@cern.ch>
 
 	* Adding WriterFLAT and yoda2flat
 
 2012-11-16  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding YODA/ROOTCnv.h. for data object converter functions. Two
 	(untested) functions added for TH1 -> YODA.
 
 	* Adding toIntegralHisto(Histo1D&) function.
 
 2012-11-15  Dave Mallows  <dave.mallows@gmail.com>
 
 	* Commited numerous changes to Axis2D. Axis2D now uses BinSearcher as
 	with Axis1D.
 
 2012-11-15  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Improving division and efficiency treatments, and allowing
 	arbitrary f(x), f(y), and flip transformations on Scatter2D.
 
 2012-11-14  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Converting linspace, logspace, and their usage to place the nbins argument first.
 
 2012-08-07  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Removing unused (beyond 2nd order) sumWXYZ counter from Dbn3D.
 
 2012-08-07  Dave Mallows  <dave.mallows@gmail.com>
 
 	* Converted Axis1D to use new Utils/BinSearcher.
 
 2012-08-02  Dave Mallows  <dave.mallows@gmail.com>
 
 	* Heavily refactored Cython bindings
 
 	* HistoBin1D, ProfileBin1D etc. now inherit from Bin1D[DBN]
 
 	* Temporarily removed Histo2D, Profile2D and Scatter3D mappings.
 
 2012-07-23  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Installing scripts from bin dir, and making the yoda2aida interface nicer.
 
 	* Adding Cython mappings for Dbn3D and Profile2D, and other fixes/improvements.
 
 2012-07-22  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding Cython mappings for Scatter3D and ProfileBin2D.
 
 	* Fixing more crap code legacy from old 2D plot implementation, this time in Scatter3D.
 
 2012-07-19  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding stdErr for Histo2D + Python mapping, and more Cython improvements.
 
 	* Adding path/title-only AO constructors and making nice Python constructor for Histo2D.
 
 	* Cython mapping improvements & additions for Point3D + Scatter3D.
 
 	* Removing mixed symm/asymm constructors on Point*D & Scatter*D classes.
 
 2012-07-12  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Reintroducing Profile2D and Scatter3D.
 
 	* Adding axis locking to Axis2D.
 
 	* Supporting Histo2D in WriterYODA.
 
 2012-07-02  Andy Buckley  <andy.buckley@cern.ch>
 
 	* More incremental progress toward a working 2D bin hash mechanism.
 
 2012-05-03  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding nice constructor behaviours to the Histo1D and Profile2D
 	Python interfaces, and adding the mkScatter operation for
 	Profile1D.
 
 	* Adding more default constructors for analysis objects, to allow
 	member variable and STL container use without pointers.
 
 2012-05-02  Andy Buckley  <andy.buckley@cern.ch>
 
 	* A much simplified and more robust rewrite of the Axis1D class,
 	just using STL map in place of the hand-written bin edge caching.
 
 	* Improvements (I hope) to the binary search in Axis1D, and
 	providing an experimental default constructor for Histo1D.
 
 2011-12-08  Hendrik Hoeth  <hendrik.hoeth@cern.ch>
 
 	* ReaderYODA can now parse Histo1D and Profile1D flat files
 
 2011-12-08  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Adding a Utils::ndarray object and using it to implement a
 	general Scatter<N> system, with generalised Point<N> and Error<N>
 	to boot.
 
 2011-12-07  Hendrik Hoeth  <hendrik.hoeth@cern.ch>
 
 	* Lots of cleanup
 
 2011-12-07  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Mapping the Dbn1D and Dbn2D classes into Python.
 
 	* Adding an outflows() accessor to Histo2D.
 
 	* Writing out total dbn lines for Histo1D and Profile1D in the
 	YODA format, and now writing out the 'cross-terms' for Profile1D,
 	too.
 
 	* Properly adding Dbn1D accessors for Histo1D.
 
 	* Updating the Cython mappings to provide the totalDbn() methods
 	and add a placeholder mapping for Dbn2D. Completed mappings are
 	needed for Dbn{1,2,3}D and the Profile types.
 
 	* Adding totalDbn() accessors to data types.
 
 2011-12-06  Andy Buckley  <andy.buckley@cern.ch>
 
 	* Making Histo1D/2D::scaleW() write a ScaledBy annotation.
 
 	* Adding annotation-fetching methods with a default return value
 	argument to AnalysisObject.
 
 	* Adding normalize() methods to Histo1D/2D.
 
 	* Adding weighted RMS calculating methods to Dbn1D, Dbn2D and
 	Bin1D/2D.
 
 2011-09-03  Dave Mallows  <dave.mallows@gmail.com>
 
 	* Fixed ReaderAIDA: x-value and low y-error interchanged when filling
 	Scatter2D.
 
 	* Changed to Cython for Python bindings: Swig bindings were in need of
 	serious amounts of work. Cython should provide a means to provide more
 	Pythonic bindings to YODA. A minimal subset of ReaderAIDA, Scatter2D
 	and Point2D have been wrapped.
 
 	* Modified configure.ac, Makefile.am and pyext/Makefile.am to reflect
 	change to Cython. Added cython.m4 from python-efl (Part of the
 	enlightenment project; LGPL)
 
 2011-08-31  Dave Mallows  <dave.mallows@gmail.com>
 
 	* Fixed python tests by installing python extension to pyext/build
 
 2011-08-23  Andy Buckley  <andy@insectnation.org>
 
 	* Adding rebinning interface to Histo1D and Profile1D, and adding
 	a test (and a new test feature for output message formatting)
 
 	* Adding first implementation of 1D bin merging to Axis1D.
 
 2011-08-22  Andy Buckley  <andy@insectnation.org>
 
 	* Adding copy constructors and assignment operators to Histo1D,
 	Profile1D, and Scatter2D, and their respective bins/points.
 
 	* Remove use of sign(weight) in filling sum(w2) -- I think this
 	was an historical attempt based on a scaling axiom which turned
 	out to be inappropriate.
 
 	* Reworking the Bin1D inheritance and composition design so that
 	all bin types store a single distribution object -- a Dbn1D for
 	histo bins and a Dbn2D for profile bins.
 
 2011-08-18  Andy Buckley  <andy@insectnation.org>
 
 	* Removing the Profile1D -> ProfileBin1D friendship. This is very
 	heartening -- the fewer friend declarations we need, the more
 	indication that the class structure is not pathological! (Or that
 	we've just made everything public... but we haven't)
 
 2011-08-15  Andy Buckley  <andy@insectnation.org>
 
 	* Inlining all functions in HistoBin1D, ProfileBin1D, and
 	HistoBin2D.
 
 	* Converting Dbn2D to be composed of two Dbn1Ds and a
 	cross-term. Also tidying the interfaces of the 2D classes and the
 	scaleX/Y methods throughout, and adding Doxygen comments.
 
 2011-08-12  Andy Buckley  <andy@insectnation.org>
 
 	* Adding proper Doxygen structures and full descriptive comments
 	to Dbn2D.
 
 	* Adding the persistency state-setting constructors for Profile1D
 	and Dbn2D.
 
 	* Inlining lots of methods on Dbn1D. Same should be done for
 	Dbn2D, but first it needs to be reimplemented in terms of two
 	Dbn1Ds + the cross-term.
 
 2011-08-11  Andy Buckley  <andy@insectnation.org>
 
 	* Various typo fixes and comments relating to persistency
 	constructors, Histo2D slicing, etc.
 
 	* Changing the HistoBin1D state-setting constructors (aargh, these
 	should *not* have already existed) to take Dbn1D as an argument
 	rather than a long list of doubles.
 
 2011-08-01  Andy Buckley  <andy@insectnation.org>
 
 	* Adding tests to check that implicit construction of Weights
 	objects from literal doubles and ints works.
 
 2011-07-28  Andy Buckley  <andy@insectnation.org>
 
 	* Bumping version number to 0.4.0beta0 -- there have been
 	substantial changes recently and YODA is now in a state where it
 	should be interesting for outsiders to start playing with it.
 
 	* Templating the Axis1D on the distribution type to be used for
 	total and under/overflow statistics: Profile1D now has Dbn2D
 	objects handling its total and overflow statistics.
 
 2011-07-26  Andy Buckley  <andy@insectnation.org>
 
 	* Added a Histo1D::integral(index1, index2) method. Not sure how
 	or if to extend this to Profile1D.
 
 	* Implementing incomplete Scatter2D operator+ and operator-
 	functions.
 
 2011-07-25  Andy Buckley  <andy@insectnation.org>
 
 	* Adding a Weights class, designed to seamlessly replace
 	double-type weights and weighted moments with a named and
 	vectorised form.
 
 2011-07-19  Andy Buckley  <andy@insectnation.org>
 
 	* Add Profile1D and Scatter2D division operators.
 
 	* Add xMin/xMax synonyms to the Axis1D, cf. the bins.
 
 2011-07-18  Andy Buckley  <andy@insectnation.org>
 
 	* Add a first stab at a Histo1D/Histo1D division operator.
 
 2011-07-10  Andy Buckley  <andy@insectnation.org>
 
 	* Add construction of Histo1Ds from Profile1D and Histo1D, and
 	construction of Profile1Ds from those and Scatter2D.
 
 2011-07-07  Andy Buckley  <andy@insectnation.org>
 
 	* Add construction of a Histo1D from Scatter2D.
 
 2011-06-15  Andy Buckley  <andy@insectnation.org>
 
 	* Making the AIDA reader work, including reading of annotations
 	and a few tweaks to the simple type persistency system. Test histo
 	1b updated.
 
 2011-06-12  Andy Buckley  <andy@insectnation.org>
 
 	* Removing Histo1D::area
 
 	* Filling and using under/overflow and total db on Histo1D, and
 	adding boolean arg to integral, sumW, etc.
 
 	* Fixing for C++ change in behaviour of std::make_pair
 
 	* Adding addAnnotation, and mapping annotations to Python.
 
 2011-02-22  Andy Buckley  <andy@insectnation.org>
 
 	* Use distutils rather than setuptools for the Python interface
 	build.
 
 	* Renaming Bin, HistoBin and ProfileBin to be Bin1D, HistoBin1D,
 	ProfileBin1D. Bin is now a top-level abstract class with minimal
 	functionality to be shared between 1D and 2D bins.
 
 2011-01-12  Andy Buckley  <andy@insectnation.org>
 
 	* Type annotations in mkScatter
 
 	* Added many vector constructors and addPoint functions to
 	Scatter2D.
 
 2011-01-11  Andy Buckley  <andy@insectnation.org>
 
 	* Add lexical_cast support to annotation get and set functions.
 
 	* Write out annotations in AIDA format, and copy annotations in
 	mkScatter -- using a new AnalysisObject::setAnnotations method.
 
 	* Convert DPS output to use interim Scatter construction
 
 	* Make (unused) yoda.plot subpackage.
 
 	* Write out annotations in YODA format.
 
 	* Make Scatter2D representations of Histo1D and Profile1D.
 
 	* Write out Scatter2D objects in AIDA and YODA formats.
 
 	* Make Scatter2D and Point2D work. Add a few extra
 	methods... evolution and tweaking required.
 
 2011-01-10  Andy Buckley  <andy@insectnation.org>
 
 	* Add Boost checks and header includes. Not used yet.
 
 	* Hide Utils:: content from Doxygen and nvector -> Utils::nvector.
 
 	* Removing unused YAML stuff: we aren't going that way for
 	persistency anymore.
 
 	* Renaming Axis -> Axis1D
 
 	* Removing dead-end templated Scatter stuff.
 
 	* Move (generated) config files into the Config subdir.
 
 	* Move sortedvector and indexedset into the Utils dir.
 
 	* Move the "utils" directory and namespace to "Utils"
 
 	* Put the Doxyfile under configure control by moving it to
 	Doxyfile.in and using the @PACKAGE_VERSION@ token.
 
 	* Make Doxygen find the .icc file and hide functions with name _*
 	and in the YAML namespace.
 
 	* Removing the Binning argument and enum in favour of explicit bin
 	edge vectors, possibly produced explicitly via the MathUtils
 	linspace and logspace functions, or the new Axis::mkBinEdgesLin/Log
 	alias functions.
 
 	* Fixed Axis, Histo1D and Profile1D constructors, by adding a path
 	argument, passing the path and title args to the AnalysisObject
 	base constructor properly.
 
 	* Removed several old and unused files such as Tree.h
 
 2011-01-09  Andy Buckley  <andy@insectnation.org>
 
 	* Updating copyright comments to be valid into 2011.
 
 	* Persistency fixes, and changing the interface to use the annotated path.
 
 	* Using annotations for path and title.
 
 	* Adding tests of collection and iterator range AO writing.
 
 	* Adding static write functions on Writer*.h implementations to
 	avoid needing to make an explicit Writer object via the create()
 	functions.
 
 	* Rename Exception.h -> Exceptions.h
 
 	* Added AnnotationError.
 
 	* Re-enable persistency of collections with begin/end iterators.
 
 2011-01-08  Andy Buckley  <andy@insectnation.org>
 
 	* Enabling quiet compilation.
 
 	* More annotation functionality.
 
 2011-01-07  Andy Buckley  <andy@insectnation.org>
 
 	* Sorting out autoheaders to be more useful.
 
 	* Rewriting AIDA writer to use DPS representation (no reloading)
 	for Histo1D and Profile1D objects.
 
 	* Adding persistency system hooks, since RTTI just sucks too much.
 
 	* Renaming test files to have more meaningful names.
 
 2010-12-10  Andy Buckley  <andy@insectnation.org>
 
 	* Some tweaks to Axis, Bin, etc. to use the sortedvector. Seems to
 	be working! (I must be checking it wrongly...)
 
 	* Adding another candidate object for the axis bin container: a
 	sorted extension to STL std::vector with an insert method. This
 	will do as a development placeholder: a proper sorted & indexed
 	container may be substituted later.
 
 	* Fix test code: titles are no longer given as histogram
 	constructor arguments.
 
 2010-11-21  Andy Buckley  <andy@insectnation.org>
 
 	* Adding indexed set for holding bins on axes. Still not sure it's
 	what we want, as (I just realised) STL sets are iterator-immutable
 	because they are self-keyed and changes to elements would also
 	change their sorting.
 
 2010-09-19  Andy Buckley  <andy@insectnation.org>
 
 	* Restarting ChangeLog contributions! Many changes in the huge
 	time since last update... activity on YODA has renewed and we have
 	a better picture of the distinctive features we require. New idea:
 	named weight vector filling, allowing "parallel" histograms for
 	various event weight variations. I/O remains an awkward issue,
 	especially since the classes are now much richer than they used to
 	be, and don't know about paths. Output can be easily put on top:
 	not an issue... and we can probably do something with
 	pickling. But reading in from C++?
 
 2008-09-16  Andy Buckley  <andy@insectnation.org>
 
 	* Moved duplicate Histo1D/Profile1D code on to Axis, making Axis a
 	templated class at the same time.
 
 2008-09-12  Andy Buckley  <andy@insectnation.org>
 
 	* Started work on a little plotting tool, initially for Herwig++
 	parton pT cut testing, but incrementally enhancing it to be a
 	command-line quick plotter seems like a good idea.
 
 	* Added some more test programs... working towards a proper test
 	suite.
 
 	* Added "no path & title" constructors - you don't always want to
 	write out the histo, since sometimes it's just a good way to
 	gather statistics.
 
 	* Fixed YODA mapping to allow use of vectors of bins as Python
 	lists.
 
 	* Added Profile1D functionality.
 
 	* Fixed Dbn1D to use sign(weight) as part of the "w**2" measure,
 	so that negative weights behave themselves.
 
 2008-05-23  Andy Buckley  <andy@insectnation.org>
 
 	* Added Dbn1D class to centralise the calculation of statistics
 	from unbounded, unbinned, weighted distributions.
 
 2008-05-15  Andy Buckley  <andy@insectnation.org>
 
 	* Added Profile1D class.
 
 	* Fixed NaN errors from zero weights.
 
 2008-04-14  Andy Buckley  <andy@insectnation.org>
 
 	* Python SWIG interface now compiles and can be used: the subtlety
 	that was breaking it was that SWIG has to be prodded in pretty
 	non-obvious ways to make std::vectors of classes without
 	default (no-arg) constructors. See
 	http://osdir.com/ml/programming.swig/2004-04/msg00011.html for
 	about the only reference to this to be found anywhere!
 
 	* Basic AIDA writer now available - it doesn't yet output all the
 	necessary information though, especially not for merging parallel
 	runs.
diff --git a/bin/yodamerge b/bin/yodamerge
--- a/bin/yodamerge
+++ b/bin/yodamerge
@@ -1,296 +1,299 @@
 #! /usr/bin/env python
 
 """\
 %prog [-o outfile] <yodafile1>[:<scale1>] <yodafile2>[:<scale1>] ...
   e.g. %prog run1.yoda run2.yoda run3.yoda  (unweighted merging of three runs)
     or %prog run1.yoda:2.0 run2.yoda:3.142  (weighted merging of two runs)
 
 Merge analysis objects from multiple YODA files, combining the statistics of
 objects whose names are found in multiple files. May be used either to merge
 disjoint collections of data objects, or to combine multiple statistically
 independent runs of the same data objects into one high-statistics run. Optional
 scaling parameters may be given to rescale the weights of the objects on a
 per-file basis before merging.
 
 By default the output is written to stdout since we can't guess what would be
 a good automatic filename choice! Use the -o option to provide an output filename.
 
 
 IMPORTANT!
   This script is not meant to handle all run merging situations or data objects:
   there are limitations to what can be inferred from data objects alone. If you
   need to do something more complex than the common cases handled by this script,
   please write your own script / program to load and process the data objects.
 
 
 SCATTERS (E.G. HISTOGRAM RATIOS) CAN'T BE MERGED
 
   Note that 'scatter' data objects, as opposed to histograms, cannot be merged
   by this tool since they do not preserve sufficient statistical
   information. The canonical example of this is a ratio plot: there are
   infinitely many combinations of numerator and denominator which could give the
   same ratio, and the result does not indicate anything about which of those
   infinite inputs is right (or the effects of correlations in the division).
 
   If you need to merge Scatter2D objects, you can write your own Python script
   or C++ program using the YODA interface, and apply whatever case-specific
   treatment is appropriate. By default the first such copy encountered will be
   returned as the 'merged' output, with no actual merging having been done.
 
 NORMALIZED, UNNORMALIZED, OR A MIX?
 
   An important detail in histogram merging is whether a statistical treatment
   for normalized or unnormalized histograms should be used: in the former case
   the normalization scaling must be undone *before* the histograms are added
   together, and then re-applied afterwards. This script examines the ScaledBy
   attribute each histograms to determine if it has been normalized. We make the
   assumption that if ScaledBy exists (i.e. h.scaleW has been called) then the
   histogram is normalized and we normalize the resulting merged histogram to the
   weighted average of input norms; if there is no ScaledBy, we assume that the
   histogram is not normalised.
 
   This is not an infallible approach, but we believe is more robust than heuristics
   to determine whether norms are sufficiently close to be considered equal.
   In complicated situations you will again be better off writing your own
   script or program to do the merging: the merging machinery of this script is
   available directly in the yoda Python module.
 
 See the source of this script (e.g. use 'less `which %prog`) for more discussion.
 """
 
 # MORE NOTES
 #
 # If all the input histograms with a particular path are found to have the same
 # normalization, and they have ScaledBy attributes indicating that a histogram
 # weight scaling has been applied in producing the input histograms, each
 # histogram in that group will be first unscaled by their appropriate factor, then
 # merged, and then re-normalized to the target value. Otherwise the weights from
 # each histogram copy will be directly added together with no attempt to guess an
 # appropriate normalization. The normalization guesses (and they are guesses --
 # see below) are made *before* application of the per-file scaling arguments.
 #
 # IMPORTANT: note from the above that this script can't work out what to do
 # re. scaling and normalization of output histograms from the input data files
 # alone. It may be possible (although unlikely) that input histograms have the
 # same normalization but are meant to be added directly. It may also be the case
 # (and much more likely) that histograms which should be normalized to a common
 # value will not trigger the appropriate treatment due to e.g. statistical
 # fluctuations in each run's calculation of a cross-section used in the
 # normalization. And anything more complex than a global scaling (e.g. calculation
 # of a ratio or asymmetry) cannot be handled at all with a post-hoc scaling
 # treatment. The --assume-normalized command line option will force all histograms
 # to be treated as if they are normalized in the input, which can be useful if
 # you know that all the output histograms are indeed of this nature. If they are
 # not, it will go wrong: you have been warned!
 #
 # Please use this script as a template if you need to do something more specific.
 #
 # NOTE: there are many possible desired behaviours when merging runs, depending on
 # the factors above as well as whether the files being merged are of homogeneous
 # type, heterogeneous type, or a combination of both. It is tempting, therefore,
 # to add a large number of optional command-line parameters to this script, to
 # handle these cases. Experience from Rivet 1.x suggests that this is a bad idea:
 # if a problem is of programmatic complexity then a command-line interface which
 # attempts to solve it in general is doomed to both failure and unusability. Hence
 # we will NOT add extra arguments for applying different merging weights or
 # strategies based on analysis object path regexes, auto-identifying 'types' of
 # run, etc., etc.: if you need to merge data files in such complex ways, please
 # use this script as a template around which to write logic that satisfies your
 # particular requirements.
 
 
 import yoda, optparse, sys, math
 
 parser = optparse.OptionParser(usage=__doc__)
 parser.add_option("-o", "--output", default="-", dest="OUTPUT_FILE", metavar="PATH",
                   help="write output to specified path")
 parser.add_option("--s1d-mode", "--s1dmode", default="assume_mean", dest="S1D_MODE", metavar="MODE",
                   help="choose strategy for combining Scatter1D objects: one of 'first', 'combine', 'assume_mean', 'add'")
 parser.add_option("--s2d-mode", "--s2dmode", default="assume_mean", dest="S2D_MODE", metavar="MODE",
                   help="choose strategy for combining Scatter2D objects: one of 'first', 'combine', 'assume_mean', 'add'")
 parser.add_option("--s3d-mode", "--s3dmode", default="assume_mean", dest="S3D_MODE", metavar="MODE",
                   help="choose strategy for combining Scatter3D objects: one of 'first', 'combine', 'assume_mean', 'add'")
 parser.add_option("--type-mismatch-mode", default="scatter", dest="TYPE_MISMATCH_MODE", metavar="MODE",
                   help="choose strategy for combining objects whose types mismatch: one of 'first', 'scatter'")
 parser.add_option("--add", "--stack", action="store_true", default=False, dest="STACK",
                   help="force simple stacking (also forces all scatter modes to 'add')")
 parser.add_option("--no-veto-empty", action="store_false", default=True, dest="VETO_EMPTY",
                   help="disable the removal of empty (sumW=0) data objects _before_ applying merge heuristics. You probably want the default!")
 parser.add_option("--assume-normalized", action="store_true", default=False, dest="ASSUME_NORMALIZED",
                   help="DEPRECATED, AND DOES NOTHING. This option _used_ to bypass the detection heuristic for unnormalized histograms")
 opts, fileargs = parser.parse_args()
 
 
 ## Include scatters in "add" mode
 if opts.STACK:
     opts.S1D_MODE = "add"
     opts.S2D_MODE = "add"
     opts.S3D_MODE = "add"
 
 
 ## Put the incoming objects into a dict from each path to a list of histos and scalings
 analysisobjects_in = {}
 for fa in fileargs:
     filename, scale = fa, 1.0
     if ":" in fa:
         try:
             filename, scale = fa.rsplit(":", 1)
             scale = float(scale)
         except:
             sys.stderr.write("Error processing arg '%s' with file:scale format\n" % fa)
     aos = yoda.read(filename)
     for aopath, ao in aos.items():
         ao.setAnnotation("yodamerge_scale", scale)
         analysisobjects_in.setdefault(aopath, []).append(ao)
 
 
 analysisobjects_out = {}
 for p, aos in analysisobjects_in.items():
 
     ## Identify the canonical aotype being handled from the type of the first entry in aos
     aotype = type(aos[0])
 
     ## Check that types match, and just output the first one if they don't
     if not all(type(ao) is aotype for ao in aos):
         msg = "WARNING: cannot merge mismatched analysis object types for path %s: " % p
         scatter_fail = False
         if opts.TYPE_MISMATCH_MODE == "scatter":
             saos = []
             for ao in aos:
                 sao = ao.mkScatter()
                 sao.setAnnotation("yodamerge_scale", ao.annotation("yodamerge_scale"))
                 saos.append(sao)
             saotype = type(saos[0])
             msg += "converting to %ss" % saotype.__name__
             if all(type(sao) is saotype for sao in saos):
                 sys.stderr.write(msg + "\n")
                 aos = saos
                 aotype = saotype
             else:
                 msg += "... failed, "
                 scatter_fail = True
         if opts.TYPE_MISMATCH_MODE == "first" or scatter_fail:
             sys.stderr.write(msg + "returning first object\n")
             analysisobjects_out[p] = aos[0]
             continue
 
 
     ## Remove empty fillable data objects, to avoid gotchas where e.g. histos are normalised and hence
     ## ScaledBy should be set... but isn't because the emptiness blocked rescaling to finite area
     if opts.VETO_EMPTY:
         # TODO: Add a Fillable interface/ABC and use that for the type matching
         if aotype in (yoda.Counter, yoda.Histo1D, yoda.Histo2D, yoda.Profile1D, yoda.Profile2D):
             aos_nonzero = [ao for ao in aos if ao.sumW() != 0] #< possible that this doesn't mean no fills :-/
             ## Just output the first histo if they are all empty
             if not aos_nonzero:
                 analysisobjects_out[p] = aos[0]
                 continue
             ## Reset aos to only contain non-empty ones
             aos = aos_nonzero
 
 
     ## Counter, Histo and Profile (i.e. Fillable) merging
     # TODO: Add a Fillable interface/ABC and use that for the type matching
     if aotype in (yoda.Counter, yoda.Histo1D, yoda.Histo2D, yoda.Profile1D, yoda.Profile2D):
 
         ## Identify a target rescaling factor from the 1/scalefactor-weighted norms of each run
         rescale = None
         if len(aos) > 1 and opts.STACK:
             pass # we're in dumb stacking mode
         elif all("ScaledBy" in ao.annotations for ao in aos):
-            rescale = 1.0 / sum(float(ao.annotation("yodamerge_scale"))/float(ao.annotation("ScaledBy")) for ao in aos)
+            try:
+                rescale = 1.0 / sum(float(ao.annotation("yodamerge_scale"))/float(ao.annotation("ScaledBy")) for ao in aos)
+            except ZeroDivisionError:
+                sys.stderr.write("WARNING: Abandoning normalized merge of path %s because ScaledBy attributes are zero.\n" % p)
         elif all("ScaledBy" not in ao.annotations for ao in aos):
             pass
         else:
             sys.stderr.write("WARNING: Abandoning normalized merge of path %s because some but not all inputs have ScaledBy attributes\n" % p)
 
         ## Now that the normalization-identifying heuristic is done, apply user scalings and undo the normalization scaling if appropriate
         for ao in aos:
             if rescale:
                 ao.scaleW( 1.0/float(ao.annotation("ScaledBy")) )
             ao.scaleW( float(ao.annotation("yodamerge_scale")) )
 
         ## Make a copy of the (scaled & unnormalized) first object as the basis for the output
         ## and merge for histograms (including weights, normalization, and user scaling)
         ao_out = aos[0].clone()
         ao_out.rmAnnotation("yodamerge_scale")
         for ao in aos[1:]:
             ao_out += ao
         if rescale:
             ao_out.scaleW(rescale)
 
 
     ## Merge for Scatters, assuming equal run sizes, and applying user scaling
     else:
 
         ## Make a copy of the first object as the basis for merging (suitable for all Scatter types)
         ao_out = aos[0].clone()
         ao_out.rmAnnotation("yodamerge_scale")
         ## If there's only one object, there's no need to do any combining
         if len(aos) == 1:
             pass
 
         elif aotype in (yoda.Scatter1D,yoda.Scatter2D,yoda.Scatter3D):
 
             ## Retrieve dimensionality of the Scatter*D object
             dim=ao_out.dim
             SND_MODE=getattr(opts,"S%dD_MODE" % dim)
             axis=['','x','y','z']
 
             ## Use asymptotic mean+stderr convergence statistics
             if SND_MODE in ("assume_mean", "add"):
 
                 msg = "WARNING: Scatter%dD %s merge assumes asymptotic statistics and equal run sizes" % (dim, p)
                 if any(float(ao.annotation("yodamerge_scale")) != 1.0 for ao in aos):
                     msg += " (+ user scaling)"
                 sys.stderr.write(msg + "\n")
                 npoints = len(ao_out.points)
                 for i in range(npoints):
                     val_i = scalesum = 0.0
                     ep_i = {} # will hold the values of the multiple error sources 
                     em_i = {} # will hold the values of the multiple error sources 
                     for ao in aos:
                         scale = float(ao.annotation("yodamerge_scale"))
                         variations=ao.variations()
                         scalesum += scale
                         val_i += scale * ao.points[i].val(dim)
                         for var in variations:
                           if not var in ep_i.keys(): 
                             ep_i[var]=0.
                             em_i[var]=0.
                           ep_i[var] += (scale * ao.points[i].errs(dim,var)[0])**2
                           em_i[var] += (scale * ao.points[i].errs(dim,var)[1])**2
                     for var in ep_i.keys(): 
                       ep_i[var] = math.sqrt(ep_i[var])
                       em_i[var] = math.sqrt(em_i[var])
                     if SND_MODE == "assume_mean":
                         val_i /= scalesum
                         for var in ep_i.keys(): 
                           ep_i[var]  /= scalesum
                           em_i[var]  /= scalesum
                     setattr(ao_out.points[i],'%s' % axis[dim], val_i)
                     for var in ep_i.keys(): 
                       #setattr(ao_out.points[i],'set%sErrs' % axis[dim].upper(), ((ep_i[var], em_i[var]),var))
                       ao_out.points[i].setErrs(dim , (ep_i[var], em_i[var]),var)
 
             ## Add more points to the output scatter
             elif SND_MODE == "combine":
                 for ao in aos[1:]:
                     ao_out.combineWith(ao)
 
             ## Just return the first AO unmodified & unmerged
             elif SND_MODE == "first":
                 pass
 
             else:
                 raise Exception("Unknown Scatter%dD merging mode:" % dim + opts.SND_MODE)
 
         ## Other data types (just warn, and write out the first object)
         else:
             sys.stderr.write("WARNING: Analysis object %s of type %s cannot be merged\n" % (p, str(aotype)))
 
     ## Put the output AO into the output dict
     analysisobjects_out[p] = ao_out
 
 ## Write output
 yoda.writeYODA(analysisobjects_out, opts.OUTPUT_FILE)