reductio/src/std.js

Reductio: Crossfilter groupings

var std = {
	add: function (prior, path) {
		return function (p, v, nf) {
			if(prior) prior(p, v, nf);
			if(path(p).count > 0) {
				path(p).std = 0.0;
				var n = path(p).sumOfSq - path(p).sum*path(p).sum/path(p).count;
				if (n>0.0) path(p).std = Math.sqrt(n/(path(p).count-1));
			} else {
				path(p).std = 0.0;
			}
			return p;
		};
	},
	remove: function (prior, path) {
		return function (p, v, nf) {
			if(prior) prior(p, v, nf);
			if(path(p).count > 0) {
				path(p).std = 0.0;
				var n = path(p).sumOfSq - path(p).sum*path(p).sum/path(p).count;
				if (n>0.0) path(p).std = Math.sqrt(n/(path(p).count-1));
			} else {
				path(p).std = 0;
			}
			return p;
		};
	},
	initial: function (prior, path) {
		return function (p) {
			p = prior(p);
			path(p).std = 0;
			return p;
		};
	}
};

export default std;