Save & Load

Pypianoroll supports efficient I/O for pypianoroll.Multitrack objects. The piano rolls will be first converted to sparse matrices (specifically, instances of scipy.sparse.csc_matrix) and then stored in a NPZ file.

Functions

pypianoroll.save(path: Union[str, pathlib.Path], multitrack: Multitrack, compressed: bool = True)

Save a Multitrack object to a NPZ file.

Parameters

• path (str or Path) – Path to the NPZ file to save.

• multitrack (pypianoroll.Multitrack) – Multitrack to save.

• compressed (bool, default: True) – Whether to save to a compressed NPZ file.

Notes

To reduce the file size, the piano rolls are first converted to instances of scipy.sparse.csc_matrix. The component arrays are then collected and saved to a npz file.

See also

pypianoroll.load()

Load a NPZ file into a Multitrack object.

pypianoroll.write()

Write a Multitrack object to a MIDI file.

Note

The saved .npz file is basically a zip archive which contains the following files:

• component arrays of the piano rolls in compressed sparse column format:

  • pianoroll_[index]_csc_data.npy

  • pianoroll_[index]_csc_indices.npy

  • pianoroll_[index]_csc_indptr.npy

• tempo.npy: the tempo array

• downbeat.npy: the down beat array

• info.json: a JSON file that contains meta data and track information

pypianoroll.load(path: Union[str, pathlib.Path]) → pypianoroll.multitrack.Multitrack

Load a NPZ file into a Multitrack object.

Supports only files previously saved by pypianoroll.save().

Parameters

path (str or Path) – Path to the file to load.

See also

pypianoroll.save()

Save a Multitrack object to a NPZ file.

pypianoroll.read()

Read a MIDI file into a Multitrack object.