Find runs of consecutive items in a numpy array.

find_runs.py

import numpy as np


def find_runs(x):
    """Find runs of consecutive items in an array."""

    # ensure array
    x = np.asanyarray(x)
    if x.ndim != 1:
        raise ValueError('only 1D array supported')
    n = x.shape[0]

    # handle empty array
    if n == 0:
        return np.array([]), np.array([]), np.array([])

    else:
        # find run starts
        loc_run_start = np.empty(n, dtype=bool)
        loc_run_start[0] = True
        np.not_equal(x[:-1], x[1:], out=loc_run_start[1:])
        run_starts = np.nonzero(loc_run_start)[0]

        # find run values
        run_values = x[loc_run_start]

        # find run lengths
        run_lengths = np.diff(np.append(run_starts, n))

        return run_values, run_starts, run_lengths

This is great! Just what I needed, thank you. Included in my research code with attribution.

Glad it's useful!

Btw, if anyone needs an artihmetic RLE library, check out https://github.com/pyranges/pyrle :)

Btw, if anyone needs an artihmetic RLE library, check out https://github.com/pyranges/pyrle :)

👍

Thank you :)

Thanks! This is exactly what I needed!

Thanks! Nice work, just what I want!

膜拜大佬

Very good! Thanks.

Thanks finally a solution that works as intended