# doc:slow-example
"""
================================
Compute ICA components on epochs
================================

ICA is fit to MEG raw data.
We assume that the non-stationary EOG artifacts have already been removed.
The sources matching the ECG are automatically found and displayed.

Note that this example does quite a bit of processing, so even on a
fast machine it can take about a minute to complete.
"""

# Authors: Denis Engemann <denis.engemann@gmail.com>
#
# License: BSD (3-clause)

import mne
from mne.preprocessing import ICA, create_ecg_epochs
from mne.datasets import sample

print(__doc__)

###############################################################################
# Read and preprocess the data. Preprocessing consists of:
#
# - meg channel selection
#
# - 1 - 30 Hz band-pass IIR filter
#
# - epoching -0.2 to 0.5 seconds with respect to events

data_path = sample.data_path()
raw_fname = data_path + '/MEG/sample/sample_audvis_filt-0-40_raw.fif'

raw = mne.io.read_raw_fif(raw_fname, preload=True)
raw.pick_types(meg=True, eeg=False, exclude='bads', stim=True)
raw.filter(1, 30)

# longer + more epochs for more artifact exposure
events = mne.find_events(raw, stim_channel='STI 014')
epochs = mne.Epochs(raw, events, event_id=None, tmin=-0.2, tmax=0.5)

###############################################################################
# Fit ICA model using the FastICA algorithm, detect and plot components
# explaining ECG artifacts.

ica = ICA(n_components=0.95, method='fastica').fit(epochs)

ecg_epochs = create_ecg_epochs(raw, tmin=-.5, tmax=.5)
ecg_inds, scores = ica.find_bads_ecg(ecg_epochs)

ica.plot_components(ecg_inds)

###############################################################################
# Plot properties of ECG components:
ica.plot_properties(epochs, picks=ecg_inds)