Issue with Whisker Length Calculation

[datavisyn]

Issue with Whisker Length Calculation

[sgratzl]

Actually in the latest version:

chartjs-chart-box-and-violin-plot/src/data.js

Lines 9 to 37 in 15a2b69

	export function whiskers(boxplot, arr) {
	const iqr = boxplot.q3 - boxplot.q1;
	// since top left is max
	let whiskerMin = Math.max(boxplot.min, boxplot.q1 - iqr);
	let whiskerMax = Math.min(boxplot.max, boxplot.q3 + iqr);
	if (Array.isArray(arr)) {
	// compute the closest real element
	for (let i = 0; i < arr.length; i++) {
	const v = arr[i];
	if (v >= whiskerMin) {
	whiskerMin = v;
	break;
	}
	}
	for (let i = arr.length - 1; i >= 0; i--) {
	const v = arr[i];
	if (v <= whiskerMax) {
	whiskerMax = v;
	break;
	}
	}
	}
	return {
	whiskerMin,
	whiskerMax
	};
	}

given an array of sorted values arr the lower whisker is computed as the value of the first element in the sorted array that is bigger than Q1 - IQR * 1.5. The upper whisker is the value of the last element that is smaller than Q3 + IQR * 1.5 accordingly. Thus, the lower whisker is at least the minimal value of the array if Q1 - IQR * 1.5 < min since the minimal value represents the first element in the array. I think this implementation is pretty standard similar how R is computing boxplots.

However, if you wanna customize it you have the option to provide the already computed boxplots statistics to the plugin instead of the plain array. See https://github.com/datavisyn/chartjs-chart-box-and-violin-plot#data-structure.

[gkemp94]

After looking more at the data structure link, I understand now that I can pass in whiskerMax & whiskerMin to the boxplot and that works. Thanks for pointing me in the correct direction.