amads.time.durdist2

amads.time.durdist2#

Distribution of duration pairs in a Score.

Author: [Yiming Huang, Roger Dannenberg]

Date: [2024-12-04]

Description:

Compute the second-order duration distribution of notes in a musical score.

Dependencies:

  • amads

  • math

Usage:

[Add basic usage examples or import statements]

Original doc: https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=6e06906ca1ba0bf0ac8f2cb1a929f3be95eeadfa#page=59

amads.time.durdist2.duration_distribution_2(score, name='Duration Pairs Distribution', bin_centers=None) → Distribution[source]#

Returns the 2nd-order duration distribution of a musical score.

Each duration is assigned to one of 9 bins.

The default centers of the bins are on a logarithmic scale as follows:

component bin center (in units of quarters) 0 1/4 (sixteenth) 1 sqrt(2)/4 2 1/2 (eighth) 3 sqrt(2)/2 4 1 (quarter) 5 sqrt(2) 6 2 (half) 7 2*sqrt(2) 8 4 (whole)

Durations below sqrt(2)/8 quarters (just above a sixteenth triplet) and greater than sqrt(2) * 4 quarters (about 5.65685 beats) are ignored.

If bin_centers is provided, the centers of the bins are set to the values in bin_centers and rounding is done on a log scale, i.e. the boundary between x1 and x2 (bin centers) is sqrt(x1 * x2). Any duration below the lower boundary is assigned to the first bin, and any duration above the upper boundary is assigned to the last bin.

The result is a NxN matrix where N is the number of bins. The matrix is m[row][col] = proportion of notes where duration indicated by row is followed by duration indicated by col.

Args:

score (Score): The musical score to analyze. name (str): A name for the distribution and plot title. bin_centers (Union[list[float], None]): bin centers (optional)

Returns:

Distribution: containing 9x9 matrix of the distribution of note durations. The matrix (data attribute of the Distribution object) has m[row][col] = proportion of notes where duration indicated by row is followed by duration indicated by col.

Raises:

Exception: If the score is not monophonic (e.g. contains chords)

Parameters:

  • score (Score)

  • name (str)

  • bin_centers (Optional[list[float]])

Return type:

Distribution

amads.time.durdist2.update_dd(dd, bin_boundaries, prev_bin, note) → int[source]#

Updates the duration distribution matrix based on the given notes.

Serves as a helper function for duration_distribution_2.

Args:

dd (List[List[float]]): The duration distribution matrix to be updated. bin_boundaries (Union[None, List[float]]): The boundaries of the bins

or None to use default bins.

prev_bin (int): The previous bin index. note (Note): The note to be processed.

Returns:

int bin number for Note if Note was used to add a count to dd, else None (which become prev_bin on the next call and is used to control whether the next note provides a count to dd).

Parameters:

  • dd (List[List[float]])

  • bin_boundaries (Optional[List[float]])

  • prev_bin (int)

  • note (Note)

Return type:

int

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