Get the directional phase sign for each sample in depths

    Args
    ----
    n_samples: int
        Length of output phase array
    des_mask: numpy.ndarray, shape (n,)
        Boolean mask of values where animal is descending
    asc_mask: numpy.ndarray, shape(n,)
        Boolean mask of values where animal is ascending

    Returns
    -------
    phase: numpy.ndarray, shape (n,)
        Signed integer array values representing animal's dive phase

        *Phases*:

        *  0: neither ascending/descending
        *  1: ascending
        * -1: descending.

def get_phase(n_samples, des_mask, asc_mask):
    '''Get the directional phase sign for each sample in depths

    Args
    ----
    n_samples: int
        Length of output phase array
    des_mask: numpy.ndarray, shape (n,)
        Boolean mask of values where animal is descending
    asc_mask: numpy.ndarray, shape(n,)
        Boolean mask of values where animal is ascending

    Returns
    -------
    phase: numpy.ndarray, shape (n,)
        Signed integer array values representing animal's dive phase

        *Phases*:

        *  0: neither ascending/descending
        *  1: ascending
        * -1: descending.
    '''
    import numpy

    phase = numpy.zeros(n_samples, dtype=int)
    phase[asc_mask] =  1
    phase[des_mask] = -1

    return phase