An example of a lag-limited correlation function for spike train data.

xcorr_maxlag.py

"""
Limited-lag numpy implementation of spike train cross-correlation.
"""

import numpy as np


def xcorr(a, b, maxlag=1.0, bins=128):
    """
    Compute the cross-correlogram of two spike train arrays.
    """
    if bins % 2 == 0:
        bins += 1
    edges = np.linspace(-maxlag, maxlag, bins + 1)

    nb = b.size
    start = end = 0
    H = np.zeros(bins)
    for t in a:
        while b[start] < t - maxlag:
            start += 1
        while end < nb and b[end] <= t + maxlag:
            end += 1
        H += np.histogram(b[start:end] - t, bins=edges)[0]

    centers = (edges[:-1] + edges[1:]) / 2
    return H, centers