Data

The public source of truth is BCI Competition IV, data set 2a.

• Dataset page: https://www.bbci.de/competition/iv/
• Raw GDF archive: https://www.bbci.de/competition/download/competition_iv/BCICIV_2a_gdf.zip
• True-label archive: https://www.bbci.de/competition/iv/results/ds2a/true_labels.zip

The packaged processed dataset uses six files:

• X_train_valid.npy
• y_train_valid.npy
• person_train_valid.npy
• X_test.npy
• y_test.npy
• person_test.npy

Post-processed .npy files under data/processed/ are versioned with Git LFS so the examples can run from a fresh clone. Raw archives, extracted GDF files, local caches, and intermediate conversion folders stay out of Git.

Before adding or updating processed arrays, install Git LFS and initialize it once:

git lfs install
git lfs track "data/processed/*.npy"

The tracked files are:

• data/processed/X_train_valid.npy
• data/processed/y_train_valid.npy
• data/processed/person_train_valid.npy
• data/processed/X_test.npy
• data/processed/y_test.npy
• data/processed/person_test.npy

The processed arrays are intentionally excluded from PyPI distributions. PyPI users should download or regenerate the data with the commands below.

Download Raw Data

python -m eegclassify.cli download-bci2a --raw-dir data/raw

Regenerate The Processed Dataset

python -m eegclassify.cli prepare-bci2a \
  --raw-dir data/raw \
  --output-dir data/processed_regenerated \
  --manifest data/processed_regenerated/manifest.json

The default converter uses the training GDF files A01T.gdf through A09T.gdf, extracts the first 22 EEG channels, uses 1000 samples starting one sample after cue onset, and applies the package split map. A trial-block split is still available with --split-map none.

Compare Processed Outputs

python -m eegclassify.cli compare-data \
  --generated-dir data/processed_regenerated \
  --reference-dir data/processed \
  --output artifacts/data_comparison.json

The comparison report includes shapes, dtypes, SHA256 hashes, label counts, subject counts, exact-match flags, and numeric differences.

The data postprocessing notebook runs the same workflow interactively.