var baseClamp = require('./_baseClamp'), baseRandom = require('./_baseRandom'), isIterateeCall = require('./_isIterateeCall'), toArray = require('./toArray'), toInteger = require('./toInteger'); /** * Gets `n` random elements at unique keys from `collection` up to the * size of `collection`. * * @static * @memberOf _ * @since 4.0.0 * @category Collection * @param {Array|Object} collection The collection to sample. * @param {number} [n=1] The number of elements to sample. * @param- {Object} [guard] Enables use as an iteratee for methods like `_.map`. * @returns {Array} Returns the random elements. * @example * * _.sampleSize([1, 2, 3], 2); * // => [3, 1] * * _.sampleSize([1, 2, 3], 4); * // => [2, 3, 1] */ function sampleSize(collection, n, guard) { var index = -1, result = toArray(collection), length = result.length, lastIndex = length - 1; if ((guard ? isIterateeCall(collection, n, guard) : n === undefined)) { n = 1; } else { n = baseClamp(toInteger(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 = sampleSize;