def slice_pointframe_by_time(pointframe, start_time, end_time):
    """ Create a temporal slice of a pointframe

    Slice a pointframe, so that only points within the
    limits defined will be kept, regardless of the text labels

    Arguments:
    pointframe -- the input pointframe to be sliced
    start_time, end_time -- define a time region

    """
    return pointframe[pointframe['time'].map(lambda x: x >= start_time \
                                                 and x <= end_time)]