def get_row_pct(row_sizes):
    """Get the span of each chromosome as a percentage of the span of the largest row

    :param list row_sizes: List of lists of chromosome sizes by row

    :returns: List of lists of chromosome sizes as percentages by row
    """

    biggest_row = max([sum(row) for row in row_sizes])
    row_pcts = [[float(val) / biggest_row for val in row] for row in row_sizes]
    return row_pcts