Cross-Session on Multiple Datasets

This example shows how to perform a cross-session analysis on two MI datasets using a CSP+LDA pipeline

The cross session evaluation context will evaluate performance using a leave one session out cross-validation. For each session in the dataset, a model is trained on every other session and performance are evaluated on the current session.

# Authors: Sylvain Chevallier <sylvain.chevallier@uvsq.fr>
#
# License: BSD (3-clause)

import warnings

import matplotlib.pyplot as plt
import seaborn as sns
from mne.decoding import CSP
from sklearn.discriminant_analysis import LinearDiscriminantAnalysis as LDA
from sklearn.pipeline import make_pipeline

import moabb
from moabb.datasets import BNCI2014_001, Zhou2016
from moabb.evaluations import CrossSessionEvaluation
from moabb.paradigms import LeftRightImagery


warnings.simplefilter(action="ignore", category=FutureWarning)
warnings.simplefilter(action="ignore", category=RuntimeWarning)
moabb.set_log_level("info")

Loading Dataset

Load 2 subjects of BNCI 2014-004 and Zhou2016 datasets, with 2 session each

subjects_list = [1, 2]

datasets = [Zhou2016(), BNCI2014_001()]

for d in datasets:
    # replace the subject list
    d.subject_list = subjects_list

Choose Paradigm

We select the paradigm MI, applying a bandpass filter (8-35 Hz) on the data and we will keep only left- and right-hand motor imagery

paradigm = LeftRightImagery(fmin=8, fmax=35)

Create Pipelines

Use the Common Spatial Patterns with 8 components and a Linear Discriminant Analysis classifier.

pipeline = {}
pipeline["CSP+LDA"] = make_pipeline(CSP(n_components=8), LDA())

Get Data (optional)

To get access to the EEG signals downloaded from the dataset, you could use dataset.get_data(subjects=[subject_id]) to obtain the EEG under an MNE format, stored in a dictionary of sessions and runs. Otherwise, paradigm.get_data(dataset=dataset, subjects=[subject_id]) allows to obtain the EEG data in sklearn format, the labels and the meta information. The data are preprocessed according to the paradigm requirements.

# X_all, labels_all, meta_all = [], [], []
# for d in datasets:
#     # sessions = d.get_data(subjects=[2])
#     X, labels, meta = paradigm.get_data(dataset=d, subjects=[2])
#     X_all.append(X)
#     labels_all.append(labels)
#     meta_all.append(meta)

Evaluation

The evaluation will return a DataFrame containing a single AUC score for each subject / session of the dataset, and for each pipeline.

overwrite = True  # set to True if we want to overwrite cached results

evaluation = CrossSessionEvaluation(
    paradigm=paradigm, datasets=datasets, suffix="examples", overwrite=overwrite
)
results = evaluation.process(pipeline)

print(results.head())

     score      time  ...  pipeline                  codecarbon_task_name
0  0.85113  0.238301  ...   CSP+LDA  2a2d47ea-9db4-4e4b-8d83-6fe6fbed2437
1  0.93640  0.228982  ...   CSP+LDA  a619d0cb-8b25-49d8-a045-f829fecd6f70
2  0.93960  0.215876  ...   CSP+LDA  5c997420-9339-41a6-9e0d-918be8bcd1dd
3  0.90800  0.238401  ...   CSP+LDA  2e788aaf-ea89-4aa4-ac3e-5c9e3f81038c
4  0.77037  0.234039  ...   CSP+LDA  73a3658f-aa07-46db-8d09-bd8dd8ed33ec

[5 rows x 13 columns]

Plot Results

Here we plot the results, indicating the score for each session and subject

sns.catplot(
    data=results,
    x="session",
    y="score",
    hue="subject",
    col="dataset",
    kind="bar",
    palette="viridis",
)
plt.show()