def _onpick(event):
    """
    pick function for interactive points
    """
    scat = event.artist
    poly = scat._polyline
    pl = len(poly)
    if scat._print:
        msg = '{}'.format(poly)
        if pl > 1:
            msg += ' exactly in {}'.format(poly[event.ind])
        print(msg)
    scat._print = not scat._print
    scat._facecolors[:, :3] = 1 - scat._facecolors[:, :3]
    scat._edgecolors[:, :3] = 1 - scat._edgecolors[:, :3]
    scat._sizes = scat._sizes * scat._sizes_offset
    scat._sizes_offset = 1 / scat._sizes_offset
    scat.figure.canvas.draw()
