def pairwise_hamming_distance(array1, array2):
    """**Experimental function**.

    Calculate hamming dissimilarity measure between two sets of
    vectors.

    Parameters
    ----------
    array1 : (P1, D) array
        P1 vectors of size D.
    array2 : (P2, D) array
        P2 vectors of size D.

    Returns
    -------
    distance : (P1, P2) array of dtype float
        2D ndarray with value at an index (i, j) representing the hamming
        distance in the range [0, 1] between ith vector in array1 and jth
        vector in array2.

    """
    distance = (array1[:, None] != array2[None]).mean(axis=2)
    return distance