def center_vector(vec, newlen):
    """
    Returns the center `newlen` portion of a vector.

    Adapted from scipy.signal.signaltools._centered:
    github.com/scipy/scipy/blob/v0.18.0/scipy/signal/signaltools.py#L236-L243

    """
    currlen = vec.shape[-1]
    startind = (currlen - newlen) // 2
    endind = startind + newlen
    return vec[startind:endind]