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Merge pull request #486 from kitcambridge/uniq

`_.uniq()` should work with sparse arrays.
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2 parents 23931b2 + 8808f7d commit c99cfca75e850702ceeadd65ccd2ae543f58f4ab @jashkenas committed Feb 21, 2012
Showing with 30 additions and 6 deletions.
  1. +22 −0 test/arrays.js
  2. +8 −6 underscore.js
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@@ -89,6 +89,28 @@ $(document).ready(function() {
var result = (function(){ return _.uniq(arguments); })(1, 2, 1, 3, 1, 4);
equal(result.join(', '), '1, 2, 3, 4', 'works on an arguments object');
+
+ var list = [];
+ list[2] = list[3] = null;
+ list[8] = 2;
+ list[10] = 2;
+ list[11] = 5;
+ list[14] = 5;
+ list[16] = 8;
+ list[19] = 8;
+ list[26] = list[29] = undefined;
+ list[33] = "hi";
+
+ var result = _.uniq(list, true);
+ if (0 in [undefined]) {
+ // According to the JScript ES 3 spec, section 2.1.26, JScript 5.x (IE <=
+ // 8) treats `undefined` elements in arrays as elisions.
+ deepEqual(result, [null, 2, 5, 8, undefined, "hi"], "Works with sorted sparse arrays");
+ equal(result.length, 6, "The resulting array should not be sparse");
+ } else {
+ deepEqual(result, [null, 2, 5, 8, "hi"], "Works with sorted sparse arrays where `undefined` elements are elided");
+ equal(result.length, 5, "The resulting array should not be sparse");
+ }
});
test("arrays: intersection", function() {
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@@ -372,15 +372,17 @@
// Aliased as `unique`.
_.uniq = _.unique = function(array, isSorted, iterator) {
var initial = iterator ? _.map(array, iterator) : array;
- var result = [];
- _.reduce(initial, function(memo, el, i) {
- if (0 == i || (isSorted === true ? _.last(memo) != el : !_.include(memo, el))) {
- memo[memo.length] = el;
- result[result.length] = array[i];
+ var results = [];
+ // The `isSorted` flag is irrelevant if the array only contains two elements.
+ if (array.length < 3) isSorted = true;
+ _.reduce(initial, function (memo, value, index) {
+ if (isSorted ? _.last(memo) !== value || !memo.length : !_.include(memo, value)) {
+ memo.push(value);
+ results.push(array[index]);
}
return memo;
}, []);
- return result;
+ return results;
};
// Produce an array that contains the union: each distinct element from all of

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