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Add d3.pairs.
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5 files changed

Lines changed: 43 additions & 5 deletions

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‎d3.js‎

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@@ -147,6 +147,11 @@ d3 = function() {
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while (i--) permutes[i] = array[indexes[i]];
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return permutes;
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};
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d3.pairs = function(array) {
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var pairs = [], i = 0, n = array.length, p0, p1 = array[i];
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while (++i < n) pairs.push([ p0 = p1, p1 = array[i] ]);
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return pairs;
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};
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d3.zip = function() {
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if (!(n = arguments.length)) return [];
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for (var i = -1, m = d3.min(arguments, d3_zipLength), zips = new Array(m); ++i < m; ) {

‎d3.min.js‎

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‎src/arrays/index.js‎

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@@ -10,6 +10,7 @@ import "quantile";
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import "bisect";
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import "shuffle";
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import "permute";
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import "pairs";
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import "zip";
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import "transpose";
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import "keys";

‎src/arrays/pairs.js‎

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@@ -0,0 +1,5 @@
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d3.pairs = function(array) {
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var pairs = [], i = 0, n = array.length, p0, p1 = array[i];
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while (++i < n) pairs.push([p0 = p1, p1 = array[i]]);
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return pairs;
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};

‎test/arrays/pairs-test.js‎

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var vows = require("vows"),
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load = require("../load"),
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assert = require("../assert");
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var suite = vows.describe("d3.pairs");
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suite.addBatch({
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"pairs": {
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topic: load("arrays/pairs").expression("d3.pairs"),
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"returns the empty array if input array has length less than two": function(pairs) {
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assert.deepEqual(pairs([]), []);
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assert.deepEqual(pairs([1]), []);
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},
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"returns pairs of adjacent elements in the given array": function(pairs) {
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assert.deepEqual(pairs([1, 2]), [[1, 2]]);
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assert.deepEqual(pairs([1, 2, 3]), [[1, 2], [2, 3]]);
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var a = {}, b = {}, c = {}, d = {};
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assert.deepEqual(pairs([a, b, c, d]), [[a, b], [b, c], [c, d]]);
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},
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"includes null or undefined elements in pairs": function(pairs) {
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assert.deepEqual(pairs([1, null, 2]), [[1, null], [null, 2]]);
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assert.deepEqual(pairs([1, 2, undefined]), [[1, 2], [2, undefined]]);
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}
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}
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});
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suite.export(module);

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