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67 lines
2.3 KiB
JavaScript
67 lines
2.3 KiB
JavaScript
9 years ago
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var createAggregator = require('../internal/createAggregator');
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/**
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* Creates an array of elements split into two groups, the first of which
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* contains elements `predicate` returns truthy for, while the second of which
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* contains elements `predicate` returns falsey for. The predicate is bound
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* to `thisArg` and invoked with three arguments: (value, index|key, collection).
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*
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* If a property name is provided for `predicate` the created `_.property`
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* style callback returns the property value of the given element.
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*
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* If a value is also provided for `thisArg` the created `_.matchesProperty`
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* style callback returns `true` for elements that have a matching property
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* value, else `false`.
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*
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* If an object is provided for `predicate` the created `_.matches` style
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* callback returns `true` for elements that have the properties of the given
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* object, else `false`.
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*
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* @static
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* @memberOf _
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* @category Collection
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* @param {Array|Object|string} collection The collection to iterate over.
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* @param {Function|Object|string} [predicate=_.identity] The function invoked
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* per iteration.
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* @param {*} [thisArg] The `this` binding of `predicate`.
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* @returns {Array} Returns the array of grouped elements.
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* @example
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*
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* _.partition([1, 2, 3], function(n) {
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* return n % 2;
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* });
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* // => [[1, 3], [2]]
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*
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* _.partition([1.2, 2.3, 3.4], function(n) {
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* return this.floor(n) % 2;
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* }, Math);
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* // => [[1.2, 3.4], [2.3]]
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*
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* var users = [
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* { 'user': 'barney', 'age': 36, 'active': false },
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* { 'user': 'fred', 'age': 40, 'active': true },
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* { 'user': 'pebbles', 'age': 1, 'active': false }
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* ];
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*
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* var mapper = function(array) {
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* return _.pluck(array, 'user');
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* };
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*
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* // using the `_.matches` callback shorthand
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* _.map(_.partition(users, { 'age': 1, 'active': false }), mapper);
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* // => [['pebbles'], ['barney', 'fred']]
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*
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* // using the `_.matchesProperty` callback shorthand
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* _.map(_.partition(users, 'active', false), mapper);
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* // => [['barney', 'pebbles'], ['fred']]
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*
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* // using the `_.property` callback shorthand
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* _.map(_.partition(users, 'active'), mapper);
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* // => [['fred'], ['barney', 'pebbles']]
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*/
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var partition = createAggregator(function(result, value, key) {
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result[key ? 0 : 1].push(value);
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}, function() { return [[], []]; });
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module.exports = partition;
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