Method cluster_width

source/matplot/axes_objects/bars.cpp:120–123

    }

    double bars::cluster_width() {
        // actual width of the cluster (clusters don't take all their space)
        return range_for_cluster() * (ys_.size() == 1 ? 1.0 : cluster_width_);
    }

    double bars::range_for_cluster() {
        // double min_x_diff = x_minimum_difference();