Remap MEG channel typesΒΆ

In this example, MEG data are remapped from one channel type to another. This is useful to:

  • visualize combined magnetometers and gradiometers as magnetometers or gradiometers.
  • run statistics from both magnetometers and gradiometers while working with a single type of channels.
  • ../../_images/sphx_glr_plot_virtual_evoked_001.png
  • ../../_images/sphx_glr_plot_virtual_evoked_002.png
  • ../../_images/sphx_glr_plot_virtual_evoked_003.png
  • ../../_images/sphx_glr_plot_virtual_evoked_004.png

Out:

Reading /home/ubuntu/mne_data/MNE-sample-data/MEG/sample/sample_audvis-ave.fif ...
    Read a total of 4 projection items:
        PCA-v1 (1 x 102) active
        PCA-v2 (1 x 102) active
        PCA-v3 (1 x 102) active
        Average EEG reference (1 x 60) active
    Found the data of interest:
        t =    -199.80 ...     499.49 ms (Left Auditory)
        0 CTF compensation matrices available
        nave = 55 - aspect type = 100
Projections have already been applied. Setting proj attribute to True.
Applying baseline correction (mode: mean)
    Computing dot products for 305 coils...
    Computing cross products for coils 305 x 102 coils...
    Preparing the mapping matrix...
    [Truncate at 209 missing 0.0001]
    Computing dot products for 305 coils...
    Computing cross products for coils 305 x 203 coils...
    Preparing the mapping matrix...
    [Truncate at 209 missing 0.0001]

# Author: Mainak Jas <mainak.jas@telecom-paristech.fr>

# License: BSD (3-clause)

import mne
from mne.datasets import sample

print(__doc__)

# read the evoked
data_path = sample.data_path()
fname = data_path + '/MEG/sample/sample_audvis-ave.fif'
evoked = mne.read_evokeds(fname, condition='Left Auditory', baseline=(None, 0))

# go from grad + mag to mag
virt_evoked = evoked.as_type('mag')
evoked.plot_topomap(ch_type='mag', title='mag (original)')
virt_evoked.plot_topomap(ch_type='mag',
                         title='mag (interpolated from mag + grad)')

# go from grad + mag to grad
virt_evoked = evoked.as_type('grad')
evoked.plot_topomap(ch_type='grad', title='grad (original)')
virt_evoked.plot_topomap(ch_type='grad',
                         title='grad (interpolated from mag + grad)')

Total running time of the script: ( 0 minutes 12.758 seconds)

Generated by Sphinx-Gallery