reductio/src/value-count.js

Reductio: Crossfilter groupings

import crossfilter from 'crossfilter2';

var value_count = {
	add: function (a, prior, path) {
		var i, curr;
		return function (p, v, nf) {
			if(prior) prior(p, v, nf);
			// Not sure if this is more efficient than sorting.
			i = path(p).bisect(path(p).values, a(v), 0, path(p).values.length);
			curr = path(p).values[i];
			if(curr && curr[0] === a(v)) {
				// Value already exists in the array - increment it
				curr[1]++;
			} else {
				// Value doesn't exist - add it in form [value, 1]
				path(p).values.splice(i, 0, [a(v), 1]);
			}
			return p;
		};
	},
	remove: function (a, prior, path) {
		var i;
		return function (p, v, nf) {
			if(prior) prior(p, v, nf);
			i = path(p).bisect(path(p).values, a(v), 0, path(p).values.length);
			// Value already exists or something has gone terribly wrong.
			path(p).values[i][1]--;
			return p;
		};
	},
	initial: function (prior, path) {
		return function (p) {
			p = prior(p);
			// Array[Array[value, count]]
			path(p).values = [];
			path(p).bisect = crossfilter.bisect.by(function(d) { return d[0]; }).left;
			return p;
		};
	}
};

export default value_count;