var vows = require(“vows”),
load = require("../load"), assert = require("../assert");
var suite = vows.describe(“d3.layout.histogram”);
suite.addBatch({
"histogram": { topic: load("layout/histogram").expression("d3.layout.histogram"), "defaults to frequencies": function(histogram) { var h = histogram(); assert.deepEqual(h([0,0,0,1,2,2]).map(elements), [[0, 0, 0], [], [1], [2, 2]]); }, "each bin contains the matching source elements": function(histogram) { var h = histogram(); assert.deepEqual(h([0,0,0,1,2,2]).map(elements), [[0, 0, 0], [], [1], [2, 2]]); }, "each bin also has defined x, y and dx properties": function(histogram) { var h = histogram(); assert.deepEqual(h([0,0,0,1,2,2]).map(metadata), [ {x: 0, y: 3, dx: 0.5}, {x: 0.5, y: 0, dx: 0.5}, {x: 1, y: 1, dx: 0.5}, {x: 1.5, y: 2, dx: 0.5} ]); }, "can output frequencies": function(histogram) { var h = histogram().frequency(true); assert.deepEqual(h([0,0,0,1,2,2]).map(metadata), [ {x: 0, y: 3, dx: 0.5}, {x: 0.5, y: 0, dx: 0.5}, {x: 1, y: 1, dx: 0.5}, {x: 1.5, y: 2, dx: 0.5} ]); }, "can output probabilities": function(histogram) { var h = histogram().frequency(false); assert.deepEqual(h([0,0,0,1,2,2]).map(metadata), [ {x: 0, y: 3/6, dx: 0.5}, {x: 0.5, y: 0, dx: 0.5}, {x: 1, y: 1/6, dx: 0.5}, {x: 1.5, y: 2/6, dx: 0.5} ]); }, "can specify number of bins": function(histogram) { var h = histogram().bins(2); assert.deepEqual(h([0,0,0,1,2,2]).map(elements), [ [0, 0, 0], [1, 2, 2] ]); assert.deepEqual(h([0,0,0,1,2,2]).map(metadata), [ {x: 0, y: 3, dx: 1}, {x: 1, y: 3, dx: 1} ]); }, "can specify bin thresholds": function(histogram) { var h = histogram().bins([0,1,2,3]); assert.deepEqual(h([0,0,0,1,2,2]).map(elements), [ [0, 0, 0], [1], [2, 2] ]); assert.deepEqual(h([0,0,0,1,2,2]).map(metadata), [ {x: 0, y: 3, dx: 1}, {x: 1, y: 1, dx: 1}, {x: 2, y: 2, dx: 1} ]); }, "returns the empty array with fewer than two bins": function(histogram) { var h = histogram().bins([1]); assert.deepEqual(h([0]), []); var h = histogram().bins([]); assert.deepEqual(h([0]), []); } }
});
function elements(bin) {
var array = [], i = -1, n = bin.length; while (++i < n) array.push(bin[i]); return array;
}
function metadata(bin) {
var metadata = {}; if ("x" in bin) metadata.x = bin.x; if ("y" in bin) metadata.y = bin.y; if ("dx" in bin) metadata.dx = bin.dx; return metadata;
}
suite.export(module);