115 lines
3.2 KiB
JavaScript
115 lines
3.2 KiB
JavaScript
/**
|
|
* @license Apache-2.0
|
|
*
|
|
* Copyright (c) 2018 The Stdlib Authors.
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
// MODULES //
|
|
|
|
var isCollection = require( '@stdlib/assert/is-collection' );
|
|
var isFunction = require( '@stdlib/assert/is-function' );
|
|
var validate = require( './validate.js' );
|
|
var returnValues = require( './return_values.js' );
|
|
var returnIndices = require( './return_indices.js' );
|
|
var returnPairs = require( './return_pairs.js' );
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Groups values according to an indicator function.
|
|
*
|
|
* @param {Collection} collection - collection to group
|
|
* @param {Options} [options] - function options
|
|
* @param {*} [options.thisArg] - execution context
|
|
* @param {string} [options.returns="values"] - if `values`, values are returned; if `indices`, indices are returned; if `*`, both indices and values are returned
|
|
* @param {Function} indicator - indicator function specifying which group an element in the input collection belongs to
|
|
* @throws {TypeError} first argument must be a collection
|
|
* @throws {TypeError} options argument must be an object
|
|
* @throws {TypeError} last argument must be a function
|
|
* @throws {TypeError} must provide valid options
|
|
* @returns {Object} group results
|
|
*
|
|
* @example
|
|
* function indicator( v ) {
|
|
* return v[ 0 ];
|
|
* }
|
|
* var arr = [ 'beep', 'boop', 'foo', 'bar' ];
|
|
*
|
|
* var out = groupBy( arr, indicator );
|
|
* // returns { 'b': [ 'beep', 'boop', 'bar' ], 'f': [ 'foo' ] }
|
|
*
|
|
* @example
|
|
* function indicator( v ) {
|
|
* return v[ 0 ];
|
|
* }
|
|
* var arr = [ 'beep', 'boop', 'foo', 'bar' ];
|
|
*
|
|
* var opts = {
|
|
* 'returns': 'indices'
|
|
* };
|
|
* var out = groupBy( arr, opts, indicator );
|
|
* // returns { 'b': [ 0, 1, 3 ], 'f': [ 2 ] }
|
|
*
|
|
* @example
|
|
* function indicator( v ) {
|
|
* return v[ 0 ];
|
|
* }
|
|
* var arr = [ 'beep', 'boop', 'foo', 'bar' ];
|
|
*
|
|
* var opts = {
|
|
* 'returns': '*'
|
|
* };
|
|
* var out = groupBy( arr, opts, indicator );
|
|
* // returns { 'b': [ [ 0, 'beep' ], [ 1, 'boop' ], [ 3, 'bar' ] ], 'f': [ [ 2, 'foo' ] ] }
|
|
*/
|
|
function groupBy( collection, options, indicator ) {
|
|
var opts;
|
|
var err;
|
|
var cb;
|
|
if ( !isCollection( collection ) ) {
|
|
throw new TypeError( 'invalid argument. First argument must be a collection. Value: `'+collection+'`.' );
|
|
}
|
|
opts = {
|
|
'returns': 'values'
|
|
};
|
|
if ( arguments.length === 2 ) {
|
|
cb = options;
|
|
} else {
|
|
err = validate( opts, options );
|
|
if ( err ) {
|
|
throw err;
|
|
}
|
|
cb = indicator;
|
|
}
|
|
if ( !isFunction( cb ) ) {
|
|
throw new TypeError( 'invalid argument. Last argument must be a function. Value: `'+cb+'`.' );
|
|
}
|
|
if ( opts.returns === 'values' ) {
|
|
return returnValues( collection, opts, cb );
|
|
}
|
|
if ( opts.returns === 'indices' ) {
|
|
return returnIndices( collection, opts, cb );
|
|
}
|
|
return returnPairs( collection, opts, cb );
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = groupBy;
|