Select formats based on index

[tstenner]

As a precursor for the chunk7 reader, use the same format ordering as in lsl and read in the native datatype (line 293)

[cbrnr]

Does this also do what sccn/xdf#38 proposes? If not, it would be nice if you could integrate that into this PR.

[tstenner]

Does this also do what sccn/xdf#38 proposes?

Yes, I didn't see that but it does everything sccn/xdf#38 does (and a tiny bit more). Plus, it's already in the correct repository :-)

[cbrnr]

OK great, that's what I wanted to know - so we can safely close sccn/xdf#38 once this gets merged.

[tstenner]

frombuffer doesn't need a character format string and is about 30% faster in one of my tests

[cbrnr]

We really need to set up a CI service. I don't have the time to verify if these changes (especially the switch from struct.unpack to np.frombuffer) did not introduce regressions, but by just looking at the code it LGTM. @cboulay feel free to do more checks and/or merge.

[tstenner]

I created an example file repository with a tiny (2kB) example file.

It's not a replacement for a CI, but the most basic test (python -c "import pyxdf; print(pyxdf.load_xdf('../example-files/minimal.xdf'));") produces the sample output except for the changed dtype in the output time_series:

([{'info': defaultdict(<class 'list'>, {'name': ['SendDataC'], 'type': ['EEG'], 'channel_count': ['3'], 'nominal_srate': ['10'], 'channel_format': ['int16'], 'created_at': ['50942.723319709003'], 'desc': [None], 'uid': ['xdfwriter_11_int'], 'effective_srate': 10.000000000000021}), 'footer': {'info': defaultdict(<class 'list'>, {'writer': ['LabRecorder xdfwriter'], 'first_timestamp': ['5.1'], 'last_timestamp': ['5.9'], 'sample_count': ['9'], 'clock_offsets': [defaultdict(<class 'list'>, {'offset': [defaultdict(<class 'list'>, {'time': ['50979.76'], 'value': ['-.01']}), defaultdict(<class 'list'>, {'time': ['50979.86'], 'value': ['-.02']})]})]})}, 'time_series': array([[192, 255, 238],
       [ 12,  22,  32],
       [ 13,  23,  33],
       [ 14,  24,  34],
       [ 15,  25,  35],
       [ 12,  22,  32],
       [ 13,  23,  33],
       [ 14,  24,  34],
       [ 15,  25,  35]], dtype=int16), 'time_stamps': array([5. , 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8])}, {'info': defaultdict(<class 'list'>, {'name': ['SendDataString'], 'type': ['StringMarker'], 'channel_count': ['1'], 'nominal_srate': ['10'], 'channel_format': ['string'], 'created_at': ['50942.723319709003'], 'desc': [None], 'uid': ['xdfwriter_11_int'], 'effective_srate': 10.00000000000004}), 'footer': {'info': defaultdict(<class 'list'>, {'writer': ['LabRecorder xdfwriter'], 'first_timestamp': ['5.1'], 'last_timestamp': ['5.9'], 'sample_count': ['9'], 'clock_offsets': [defaultdict(<class 'list'>, {'offset': [defaultdict(<class 'list'>, {'time': ['50979.76'], 'value': ['-.01']}), defaultdict(<class 'list'>, {'time': ['50979.86'], 'value': ['-.02']})]})]})}, 'time_series': [['<?xml version="1.0"?><info><writer>LabRecorder xdfwriter</writer><first_timestamp>5.1</first_timestamp><last_timestamp>5.9</last_timestamp><sample_count>9</sample_count><clock_offsets><offset><time>50979.76</time><value>-.01</value></offset><offset><time>50979.86</time><value>-.02</value></offset></clock_offsets></info>'], ['Hello'], ['World'], ['from'], ['LSL'], ['Hello'], ['World'], ['from'], ['LSL']], 'time_stamps': array([5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9])}], {'info': defaultdict(<class 'list'>, {'version': ['1.0']})})