Reading an event file

Read events from a file. For a more detailed guide on how to read events using MNE-Python, see Epoching and averaging (ERP/ERF).

# Authors: Alexandre Gramfort <alexandre.gramfort@telecom-paristech.fr>
#          Chris Holdgraf <choldgraf@berkeley.edu>
#
# License: BSD (3-clause)

import matplotlib.pyplot as plt
import mne
from mne.datasets import sample

print(__doc__)

data_path = sample.data_path()
fname = data_path + '/MEG/sample/sample_audvis_raw-eve.fif'

Out:

Successfully extracted to: [u'/home/ubuntu/mne_data/MNE-sample-data']

Reading events

Below we’ll read in an events file. We suggest that this file end in -eve.fif. Note that we can read in the entire events file, or only events corresponding to particular event types with the include and exclude parameters.

events_1 = mne.read_events(fname, include=1)
events_1_2 = mne.read_events(fname, include=[1, 2])
events_not_4_32 = mne.read_events(fname, exclude=[4, 32])

Events objects are essentially numpy arrays with three columns: event_sample | previous_event_id | event_id

print(events_1[:5], '\n\n---\n\n', events_1_2[:5], '\n\n')

for ind, before, after in events_1[:5]:
    print("At sample %d stim channel went from %d to %d"
          % (ind, before, after))

Out:

(array([[28771,     0,     1],
       [30450,     0,     1],
       [32101,     0,     1],
       [33712,     0,     1],
       [35428,     0,     1]], dtype=uint32), '\n\n---\n\n', array([[27977,     0,     2],
       [28771,     0,     1],
       [29652,     0,     2],
       [30450,     0,     1],
       [31240,     0,     2]], dtype=uint32), '\n\n')
At sample 28771 stim channel went from 0 to 1
At sample 30450 stim channel went from 0 to 1
At sample 32101 stim channel went from 0 to 1
At sample 33712 stim channel went from 0 to 1
At sample 35428 stim channel went from 0 to 1

Plotting events

We can also plot events in order to visualize how events occur over the course of our recording session. Below we’ll plot our three event types to see which ones were included.

fig, axs = plt.subplots(1, 3, figsize=(15, 5))

mne.viz.plot_events(events_1, axes=axs[0], show=False)
axs[0].set(title="restricted to event 1")

mne.viz.plot_events(events_1_2, axes=axs[1], show=False)
axs[1].set(title="restricted to event 1 or 2")

mne.viz.plot_events(events_not_4_32, axes=axs[2], show=False)
axs[2].set(title="keep all but 4 and 32")
plt.setp([ax.get_xticklabels() for ax in axs], rotation=45)
plt.tight_layout()
plt.show()
../../_images/sphx_glr_plot_read_events_001.png

Writing events

Finally, we can write events to disk. Remember to use the naming convention -eve.fif for your file.

mne.write_events('example-eve.fif', events_1)

Gallery generated by Sphinx-Gallery