28 lines
1011 B
JavaScript
28 lines
1011 B
JavaScript
define(['./_getLength', './_isArrayLike', './clone', './values', './random'], function (_getLength, _isArrayLike, clone, values, random) {
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// Sample **n** random values from a collection using the modern version of the
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// [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher–Yates_shuffle).
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// If **n** is not specified, returns a single random element.
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// The internal `guard` argument allows it to work with `_.map`.
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function sample(obj, n, guard) {
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if (n == null || guard) {
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if (!_isArrayLike(obj)) obj = values(obj);
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return obj[random(obj.length - 1)];
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}
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var sample = _isArrayLike(obj) ? clone(obj) : values(obj);
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var length = _getLength(sample);
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n = Math.max(Math.min(n, length), 0);
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var last = length - 1;
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for (var index = 0; index < n; index++) {
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var rand = random(index, last);
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var temp = sample[index];
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sample[index] = sample[rand];
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sample[rand] = temp;
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}
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return sample.slice(0, n);
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}
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return sample;
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});
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