'No data channels found' with plot_psd() on misc channels

Issue: Error of “No Data channels found” when attempting to plot_psd() on misc channels in a dataset which contains only misc channels. The dataset is created from raw numpy EEG data derived from a custom made device.

Platform

Platform:      Darwin-19.3.0-x86_64-i386-64bit
Python:        3.7.7 (default, Mar 10 2020, 15:43:33)  [Clang 11.0.0 (clang-1100.0.33.17)]
mne:           0.21.dev0
numpy:         1.18.2 {blas=openblas, lapack=openblas}
scipy:         1.4.1
matplotlib:    3.2.1 {backend=MacOSX}

Steps: Create mne object from raw data

mne_data = create_mne_object(channels, data, samp_freq)
print(mne_data)
print(mne_data.info)

The output is shown below.

<RawArray | 2 x 1024 (4.1 s), ~25 kB, data loaded>
<Info | 7 non-empty values
 bads: []
 ch_names: CH1, CH2
 chs: 2 MISC
 custom_ref_applied: False
 highpass: 0.0 Hz
 lowpass: 125.0 Hz
 meas_date: unspecified
 nchan: 2
 projs: []
 sfreq: 250.0 Hz
>

Time-domain data does plot correctly. However, when attempting to plot psd:

picks = mne.pick_types(mne_data.info, misc=True)
print(picks)
spect = mne_data.plot_psd(picks=picks)

Output:

[0 1]
RuntimeError: No data channels found

Summary This issue seems similar to the bug here. Is there a workaround at this point? I have tried passing picks=None without success.

[larsoner]

@drammock do you want to work on the fix? If not, I can tackle it this week

[drammock]

@gpeyton you can change the channel type with: https://mne.tools/dev/generated/mne.io.Raw.html#mne.io.Raw.set_channel_types