[Mne_analysis] ValueError: raw[1]._cals must match

[Warner, Graham Cary]

Hi all,

I'm working on a python script that makes a copy of a directory of FIFF files using python's shutil.copytree() function and then removes some metadata from each of the files in that new copy using the MNE module. It works fine on the whole but there is one particular file which, for some reason, causes the script to break. Here is the code I use and resulting error message:

>>> f = '/space/jazz/1/users/gwarner/temp_dirs_for_fiff_registration/temp_meg_storage/pp010/009/pp010_arc_raw.fif'
>>> raw = Raw(f,preload=False,verbose=False)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 2, in __init__
  File "/space/jazz/1/users/gwarner/anaconda/lib/python2.7/site-packages/mne/utils.py", line 538, in verbose
    return function(*args, **kwargs)
  File "/space/jazz/1/users/gwarner/anaconda/lib/python2.7/site-packages/mne/io/fiff/raw.py", line 114, in __init__
    _check_raw_compatibility(raws)
  File "/space/jazz/1/users/gwarner/anaconda/lib/python2.7/site-packages/mne/io/base.py", line 1995, in _check_raw_compatibility
    raise ValueError('raw[%d]._cals must match' % ri)
ValueError: raw[1]._cals must match

The strangest part is that I can open the original file without any problems:

>>> f = '/space/lilli/3/users/DARPA-TRANSFER/meg/pp010/009/pp010_arc_raw.fif'
>>> raw = Raw(f,preload=False,verbose=False)>>>

Stranger still is that the bash diff command tells me that both versions of the file are identical.

 [gwarner at jazz ~]$ diff /space/jazz/1/users/gwarner/temp_dirs_for_fiff_registration/temp_meg_storage/pp010/009/pp010_arc_raw.fif /space/lilli/3/users/DARPA-TRANSFER/meg/pp010/009/pp010_arc_raw.fif
[gwarner at jazz ~]$

The fact that it works fine for several hundred files before breaking here tells me that it isn't a problem with my implementation of the module, the fact that I can successfully open the original copy of the file tells me that it isn't just a bad/corrupted file, and the result of the diff test seems to indicate that it isn't a problem with the way it was copied either. I'm using the same version of MNE each time and have all the necessary permissions. Can anyone enlighten me as to what is going on here? Please let me know if there is any additional information I can provide to clear this up.

Thank you,
Graham
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