javafx StackedBarChart cumulative value

Question

Does anyone know how to get the cumulative value of a stacked bar chart for each X value on the category axis? Is there a method for it?

It is impossible for me to do it manually because each data series does not cover all X values and there are around 400 X values.

Thank you!

Answer 1

Assuming you have a

StackedBarChart<String, Number> chart ;

you can compute the cumulative total for each x value as

Map<String, Number> cumulativeTotal = new HashMap<>();
for (Series<String, Number> series : chart.getData()) {
    for (XYChart.Data<String, Number> data : series.getData()) {
        cumulativeTotal.merge(data.getXValue(), data.getYValue(), (y1, y2) -> y1.doubleValue() + y2.doubleValue());
    }
}

or, using streams:

Map<String, Number> cumulativeTotal = chart.getData().stream()
        .flatMap(series -> series.getData().stream())
        .collect(Collectors.toMap(Data::getXValue, Data::getYValue, (y1, y2) -> y1.doubleValue() + y2.doubleValue()));