[Mne_analysis] MNE-Python -- RawArray Info Question

Alexandre Gramfort alexandre.gramfort at telecom-paristech.fr
Thu Dec 25 11:42:18 EST 2014
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hi Sam,

> I am trying out some new preprocessing tricks recommended by some
> collaborators, which involves bandstop filtering my data to the frequencies
> of electrical artifact (60, 120, 180 Hz, etc), and subtracting the resulting
> time courses from the true data. (Their claim is that this preserves
> coherence.) To do so, I have been trying the RawArray function, but am
> having trouble passing it an Info instance. Even using the following code
> produces the error reproduced below. This is surprising, as I'm only
> translating an instance of raw to a PANDAS dataframe, and then a Numpy
> array. Any advice?

you don't need to have a pandas dataframe as you already have a numpy
array in raw._data

so raw_mat is just raw._data

also a recommendation is to never use numpy matrices but just arrays.

HTH
Alex

> raw = mne.io.Raw('some_data.fif', preload=True)
> raw_df = raw.as_data_frame()
> raw_mat = raw_df.as_matrix()
> new_raw = mne.io.RawArray(raw_mat, raw.info)
>
> ValueError                                Traceback (most recent call last)
> <ipython-input-162-10b3fdc10c23> in <module>()
>       1 raw_mat = raw.as_data_frame()
>       2 raw_mat = raw_mat.as_matrix()
> ----> 3 new_raw = mne.io.RawArray(raw_mat, raw.info)
>
> /mne/io/array/array.pyc in __init__(self, data, info, verbose)
>
> /mne/utils.pyc in verbose(function, *args, **kwargs)
>     549         return ret
>     550     else:
> --> 551         ret = function(*args, **kwargs)
>     552         return ret
>     553
>
> /usr/pubsw/packages/python/anaconda/lib/python2.7/site-packages/mne/io/array/array.pyc
> in __init__(self, data, info, verbose)
>      39
>      40         if len(data) != len(info['ch_names']):
> ---> 41             raise ValueError('len(data) does not match
> len(info["ch_names"])')
>      42         assert len(info['ch_names']) == info['nchan']
>      43
>
> ValueError: len(data) does not match len(info["ch_names"])
>
>
> Best,
> Sam Zorowitz
>
> Clinical Research Coordinator
> Department of Psychiatry: Neurosciences
> Division of Neurotherapeutics
> Massachusetts General Hospital
>
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