Error in reading ROOT files containing TMatrix and TVector

[nfoppiani]

I have been trying to read a root file containing TVector and TMatrix, the idea being following https://stackoverflow.com/questions/65833805/how-do-i-read-a-tmatrixt-with-uproot-in-python
I tried with the following code:

import uproot
file_u = uproot.open('efficiency.root')
file_u[file_u.keys()[0]]
The last line to get the first object in the file, but I get the following error:

---

TypeError Traceback (most recent call last)
in
----> 1 file_u[file_u.keys()[0]]

~/.local/lib/python3.9/site-packages/uproot/reading.py in getitem(self, where)
2043
2044 else:
-> 2045 return self.key(where).get()
2046
2047 @Property

~/.local/lib/python3.9/site-packages/uproot/reading.py in get(self)
2434
2435 try:
-> 2436 out = cls.read(chunk, cursor, context, self._file, selffile, parent)
2437
2438 except uproot.deserialization.DeserializationError:

~/.local/lib/python3.9/site-packages/uproot/model.py in read(cls, chunk, cursor, context, file, selffile, parent, concrete)
1194
1195 elif version is not None:
-> 1196 versioned_cls = cls.new_class(file, version)
1197
1198 elif context.get("in_TBranch", False):

~/.local/lib/python3.9/site-packages/uproot/model.py in new_class(cls, file, version)
1130
1131 if streamer is not None:
-> 1132 versioned_cls = streamer.new_class(file)
1133 versioned_cls.class_streamer = streamer
1134 cls.known_versions[streamer.class_version] = versioned_cls

~/.local/lib/python3.9/site-packages/uproot/streamers.py in new_class(self, file)
370 class_name = uproot.model.classname_encode(self.name, self.class_version)
371 classes = uproot.model.maybe_custom_classes(file.custom_classes)
--> 372 return uproot.deserialization.compile_class(
373 file, classes, class_code, class_name
374 )

~/.local/lib/python3.9/site-packages/uproot/deserialization.py in compile_class(file, classes, class_code, class_name)
78 setattr(uproot.dynamic, out.name, out)
79
---> 80 behaviors = tuple(_yield_all_behaviors(out, c))
81 exclude = tuple(
82 bad for cls in behaviors if hasattr(cls, "no_inherit") for bad in cls.no_inherit

~/.local/lib/python3.9/site-packages/uproot/deserialization.py in _yield_all_behaviors(cls, c)
32
33 def _yield_all_behaviors(cls, c):
---> 34 behavior_cls = uproot.behavior_of(uproot.model.classname_decode(cls.name)[0])
35 if behavior_cls is not None:
36 yield behavior_cls

~/.local/lib/python3.9/site-packages/uproot/init.py in behavior_of(classname)
227 return globals().get(name)
228 else:
--> 229 return globals().get(name)(specialization)
230
231

TypeError: 'NoneType' object is not callable
I run uproot version '4.0.10' and Python 3.9.5
If I open the same file with pyROOT I can read the TMatrix content, and it is shown as <cppyy.gbl.TMatrixT object at 0x557c36963df0>

[jpivarski]

I know what happened: the uproot.behavior_of function tries to pass template specializations to behavior classes, and TMatrix/TVector are templated. However, no specializations for these classes have been written in Python, so it was trying to pass that specialization to None.

I've moved the function (as I've been wanting to do for some time) and fixed the bug, probably, but I don't have any examples of files with a TMatrix or TVector in it. I could add such a test to the PR if you give me a few lines of PyROOT that produces one (I'm guessing that this is simpler than adding a real-data file to scikit-hep-testdata). Otherwise, could you test PR #384 with your file before I merge it and make a new release for it? Thanks!

(My preference is to add a test based on a small file made dynamically by PyROOT, if you have code for that offhand. Then the test will stay in the codebase but I won't have to mess with scikit-hep-testdata. ROOT is already a dependency for testing.)

[agoose77]

@nfoppiani does this reproduce the bug for you?

import ROOT
import uproot

path = "/tmp/test-file.root"
key = "mat"

# Write test file
f = ROOT.TFile(path, "RECREATE")
mat = ROOT.TMatrixD(3, 3)
mat[0, 1] = 4
mat[1, 0] = 8
mat[2, 2] = 3
mat.Write(key")
f.Close()

    
# Read test file
with uproot.open(path) as f:
    mat = f[key]

[jpivarski]

If the name of this class is "TMatrixD", then the template specialization that's breaking must be in a superclass. I'll try using this as a test, thanks! (If it has cls is None but specialization is not None, than it's a reproducer.)

[agoose77]

(If it has cls is None but specialization is not None, than it's a reproducer.)

This should be the case - we don't define a behaviour for TMatrix AFAICT, so the cls should be None.

[nfoppiani]

Thanks, @agoose77. Indeed I obtain the same error.
The pyROOT object mat in your code is of type <cppyy.gbl.TMatrixT<double> object at 0x55e22a3b73e0>, which is the same as the one I was encountering before, aside from the "specialization" to double.

[nfoppiani]

Otherwise, could you test PR #384 with your file before I merge it and make a new release for it? Thanks!

@jpivarski I tested PR #384 with my file and the example provided by @agoose77: it worked in both cases, and I could access the data by calling .member("fElements").

I think the dynamically generated example is good enough; otherwise, I can give you the file I was using, but it adds more complication than there needs to be, in my opinion.

[jpivarski]

The fix is in Uproot 4.0.11.