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var baseRandom = require('../internal/baseRandom'),
isIterateeCall = require('../internal/isIterateeCall'),
toArray = require('../lang/toArray'),
toIterable = require('../internal/toIterable');
/* Native method references for those with the same name as other `lodash` methods. */
var nativeMin = Math.min;
/**
* Gets a random element or `n` random elements from a collection.
*
* @static
* @memberOf _
* @category Collection
* @param {Array|Object|string} collection The collection to sample.
* @param {number} [n] The number of elements to sample.
* @param- {Object} [guard] Enables use as a callback for functions like `_.map`.
* @returns {*} Returns the random sample(s).
* @example
*
* _.sample([1, 2, 3, 4]);
* // => 2
*
* _.sample([1, 2, 3, 4], 2);
* // => [3, 1]
*/
function sample(collection, n, guard) {
if (guard ? isIterateeCall(collection, n, guard) : n == null) {
collection = toIterable(collection);
var length = collection.length;
return length > 0 ? collection[baseRandom(0, length - 1)] : undefined;
}
var index = -1,
result = toArray(collection),
length = result.length,
lastIndex = length - 1;
n = nativeMin(n < 0 ? 0 : (+n || 0), length);
while (++index < n) {
var rand = baseRandom(index, lastIndex),
value = result[rand];
result[rand] = result[index];
result[index] = value;
}
result.length = n;
return result;
}
module.exports = sample;
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