the acq_name of channel group changed after applying .filter() function

[Yuanli-Liu]

Python version

('python=3.8.5 | packaged by conda-forge | (default, Aug 29 2020, 01:22:49) \n'
 '[GCC 7.5.0]')
'os=Linux-5.4.0-52-generic-x86_64-with-glibc2.10'
'numpy=1.19.1'
'asammdf=5.22.0'

Code

MDF version

4.10

Code snippet

mf4_reader = MDF("test.mf4")
# channels_namelist is a list of channel name
mf4_reader = mf4_reader.filter(channels_namelist)
for idx, gitem in enumerate(mf4_reader.groups):
    cg = gitem["channel_group"]
    acq_name = cg.acq_name
    print(idx, cg.acq_name, sep="=>")

Description

If we comment line2: mf4_reader.filter(channels_namelist), the output is normal. Otherwise, the output of acq_name are abnormal and most of them are empty.

[Yuanli-Liu]

Similarly, after calling .filter(), the output of print(mdf.header.comment) is empty.

[JulienGrv]

mf4_reader.header.comment is empty because .filter() returns a new MDF object and you overwrite the original one in your code snippet. Regarding channel groups acq_name, if you use the development branch, I made changes and now channel groups acq_name are conserved after .filter().

Either you wait until next release or you can already try the development branch like this:
pip install git+https://github.com/danielhrisca/asammdf.git@development

Your code could then look like this:

mf4_reader = MDF("test.mf4")
# channels_namelist is a list of channel name
mf4_reader_filtered = mf4_reader.filter(channels_namelist)
print(mf4_reader.header.comment)
for idx, gitem in enumerate(mf4_reader_filtered.groups):
    cg = gitem["channel_group"]
    acq_name = cg.acq_name
    print(idx, cg.acq_name, sep="=>")

[Yuanli-Liu]

Thank you for your answer sincerely！:tada: