def __get_chart_sizes(chart_width):
    """Calculates the widths of the disparity and metric charts that make-up the concatenated chart.
    The individual widths are calculated based on the provided desired overall chart width."""

    chart_sizes = dict(
        disparity_chart_width=0.5 * chart_width, metric_chart_width=0.5 * chart_width
    )
    return chart_sizes