time-to-botec

Benchmark sampling in different programming languages
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group_by.js (3300B)

      1 /**
      2 * @license Apache-2.0
      3 *
      4 * Copyright (c) 2018 The Stdlib Authors.
      5 *
      6 * Licensed under the Apache License, Version 2.0 (the "License");
      7 * you may not use this file except in compliance with the License.
      8 * You may obtain a copy of the License at
      9 *
     10 *    http://www.apache.org/licenses/LICENSE-2.0
     11 *
     12 * Unless required by applicable law or agreed to in writing, software
     13 * distributed under the License is distributed on an "AS IS" BASIS,
     14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     15 * See the License for the specific language governing permissions and
     16 * limitations under the License.
     17 */
     18 
     19 'use strict';
     20 
     21 // MODULES //
     22 
     23 var isCollection = require( '@stdlib/assert/is-collection' );
     24 var isFunction = require( '@stdlib/assert/is-function' );
     25 var validate = require( './validate.js' );
     26 var returnValues = require( './return_values.js' );
     27 var returnIndices = require( './return_indices.js' );
     28 var returnPairs = require( './return_pairs.js' );
     29 
     30 
     31 // MAIN //
     32 
     33 /**
     34 * Groups values according to an indicator function.
     35 *
     36 * @param {Collection} collection - collection to group
     37 * @param {Options} [options] - function options
     38 * @param {*} [options.thisArg] - execution context
     39 * @param {string} [options.returns="values"] - if `values`, values are returned; if `indices`, indices are returned; if `*`, both indices and values are returned
     40 * @param {Function} indicator - indicator function specifying which group an element in the input collection belongs to
     41 * @throws {TypeError} first argument must be a collection
     42 * @throws {TypeError} options argument must be an object
     43 * @throws {TypeError} last argument must be a function
     44 * @throws {TypeError} must provide valid options
     45 * @returns {Object} group results
     46 *
     47 * @example
     48 * function indicator( v ) {
     49 *     return v[ 0 ];
     50 * }
     51 * var arr = [ 'beep', 'boop', 'foo', 'bar' ];
     52 *
     53 * var out = groupBy( arr, indicator );
     54 * // returns { 'b': [ 'beep', 'boop', 'bar' ], 'f': [ 'foo' ] }
     55 *
     56 * @example
     57 * function indicator( v ) {
     58 *     return v[ 0 ];
     59 * }
     60 * var arr = [ 'beep', 'boop', 'foo', 'bar' ];
     61 *
     62 * var opts = {
     63 *     'returns': 'indices'
     64 * };
     65 * var out = groupBy( arr, opts, indicator );
     66 * // returns { 'b': [ 0, 1, 3 ], 'f': [ 2 ] }
     67 *
     68 * @example
     69 * function indicator( v ) {
     70 *     return v[ 0 ];
     71 * }
     72 * var arr = [ 'beep', 'boop', 'foo', 'bar' ];
     73 *
     74 * var opts = {
     75 *     'returns': '*'
     76 * };
     77 * var out = groupBy( arr, opts, indicator );
     78 * // returns { 'b': [ [ 0, 'beep' ], [ 1, 'boop' ], [ 3, 'bar' ] ], 'f': [ [ 2, 'foo' ] ] }
     79 */
     80 function groupBy( collection, options, indicator ) {
     81 	var opts;
     82 	var err;
     83 	var cb;
     84 	if ( !isCollection( collection ) ) {
     85 		throw new TypeError( 'invalid argument. First argument must be a collection. Value: `'+collection+'`.' );
     86 	}
     87 	opts = {
     88 		'returns': 'values'
     89 	};
     90 	if ( arguments.length === 2 ) {
     91 		cb = options;
     92 	} else {
     93 		err = validate( opts, options );
     94 		if ( err ) {
     95 			throw err;
     96 		}
     97 		cb = indicator;
     98 	}
     99 	if ( !isFunction( cb ) ) {
    100 		throw new TypeError( 'invalid argument. Last argument must be a function. Value: `'+cb+'`.' );
    101 	}
    102 	if ( opts.returns === 'values' ) {
    103 		return returnValues( collection, opts, cb );
    104 	}
    105 	if ( opts.returns === 'indices' ) {
    106 		return returnIndices( collection, opts, cb );
    107 	}
    108 	return returnPairs( collection, opts, cb );
    109 }
    110 
    111 
    112 // EXPORTS //
    113 
    114 module.exports = groupBy;