Plot the swim speed during experimental indices

    Args
    ----
    exp_ind: ndarray
        Indices of tag data where experiment is active
    swim_speed: ndarray
        Swim speed data at sensor sampling rate

def plot_swim_speed(exp_ind, swim_speed):
    '''Plot the swim speed during experimental indices

    Args
    ----
    exp_ind: ndarray
        Indices of tag data where experiment is active
    swim_speed: ndarray
        Swim speed data at sensor sampling rate
    '''
    import numpy

    fig, ax = plt.subplots()

    ax.title.set_text('Swim speed from depth change and pitch angle (m/s^2')
    ax.plot(exp_ind, swim_speed, linewidth=_linewidth, label='speed')
    ymax = numpy.ceil(swim_speed[~numpy.isnan(swim_speed)].max())
    ax.set_ylim(0, ymax)
    ax.legend(loc='upper right')

    plt.show()

    return ax