time-to-botec

Benchmark sampling in different programming languages
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README.md (5302B)


      1 <!--
      2 
      3 @license Apache-2.0
      4 
      5 Copyright (c) 2018 The Stdlib Authors.
      6 
      7 Licensed under the Apache License, Version 2.0 (the "License");
      8 you may not use this file except in compliance with the License.
      9 You may obtain a copy of the License at
     10 
     11    http://www.apache.org/licenses/LICENSE-2.0
     12 
     13 Unless required by applicable law or agreed to in writing, software
     14 distributed under the License is distributed on an "AS IS" BASIS,
     15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     16 See the License for the specific language governing permissions and
     17 limitations under the License.
     18 
     19 -->
     20 
     21 # inmap
     22 
     23 > Invoke a function for each element in a collection and update the collection in-place.
     24 
     25 <!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
     26 
     27 <section class="intro">
     28 
     29 </section>
     30 
     31 <!-- /.intro -->
     32 
     33 <!-- Package usage documentation. -->
     34 
     35 <section class="usage">
     36 
     37 ## Usage
     38 
     39 ```javascript
     40 var inmap = require( '@stdlib/utils/inmap' );
     41 ```
     42 
     43 #### inmap( collection, fcn\[, thisArg ] )
     44 
     45 Invokes a `function` for each element in a `collection` and updates the `collection` in-place.
     46 
     47 ```javascript
     48 function scale( value, index ) {
     49     return value * index;
     50 }
     51 
     52 var arr = [ 1, 2, 3, 4 ];
     53 
     54 var out = inmap( arr, scale );
     55 // returns [ 0, 2, 6, 12 ]
     56 
     57 var bool = ( out === arr );
     58 // returns true
     59 ```
     60 
     61 The invoked `function` is provided three arguments:
     62 
     63 -   `value`: collection element
     64 -   `index`: collection index
     65 -   `collection`: input collection
     66 
     67 Basic support for dynamic collections is provided. Note, however, that index incrementation is monotonically increasing.
     68 
     69 ```javascript
     70 function scale1( value, index, collection ) {
     71     if ( index === collection.length-1 && collection.length < 10 ) {
     72         collection.push( index+2 );
     73     }
     74     return value * index;
     75 }
     76 
     77 var arr = [ 1, 2, 3, 4 ];
     78 
     79 var out = inmap( arr, scale1 );
     80 // returns [ 0, 2, 6, 12, 20, 30, 42, 56, 72, 90 ]
     81 
     82 function scale2( value, index, collection ) {
     83     collection.shift();
     84     return value * index;
     85 }
     86 
     87 arr = [ 1, 2, 3, 4 ];
     88 
     89 out = inmap( arr, scale2 );
     90 // returns [ 3, 3 ]
     91 ```
     92 
     93 To set the function execution context, provide a `thisArg`.
     94 
     95 ```javascript
     96 function sum( value ) {
     97     this.sum += value;
     98     this.count += 1;
     99     return value;
    100 }
    101 
    102 var arr = [ 1, 2, 3, 4 ];
    103 
    104 var context = {
    105     'sum': 0,
    106     'count': 0
    107 };
    108 
    109 var out = inmap( arr, sum, context );
    110 // returns [ 1, 2, 3, 4 ]
    111 
    112 var mean = context.sum / context.count;
    113 // returns 2.5
    114 ```
    115 
    116 </section>
    117 
    118 <!-- /.usage -->
    119 
    120 <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
    121 
    122 <section class="notes">
    123 
    124 ## Notes
    125 
    126 -   A `collection` may be either an [`Array`][mdn-array], [`Typed Array`][mdn-typed-array], or an array-like [`Object`][mdn-object] (excluding `strings` and `functions`).
    127 
    128 -   The function differs from [`Array.prototype.map`][mdn-array-map] in the following ways:
    129 
    130     -   The function returns the input `collection`.
    131 
    132     -   The function modifies `collection` elements in-place.
    133 
    134     -   The function does **not** skip `undefined` elements.
    135 
    136         <!-- eslint-disable no-sparse-arrays, stdlib/doctest-marker -->
    137 
    138         ```javascript
    139         function log( value, index ) {
    140             console.log( '%s: %s', index, value );
    141             return value;
    142         }
    143 
    144         var arr = [ 1, , , 4 ];
    145 
    146         var out = inmap( arr, log );
    147         /* =>
    148             0: 1
    149             1: undefined
    150             2: undefined
    151             3: 4
    152         */
    153         ```
    154 
    155     -   The function provides limited support for dynamic collections (i.e., collections whose `length` changes during execution).
    156 
    157 </section>
    158 
    159 <!-- /.notes -->
    160 
    161 <!-- Package usage examples. -->
    162 
    163 <section class="examples">
    164 
    165 ## Examples
    166 
    167 <!-- eslint no-undef: "error" -->
    168 
    169 ```javascript
    170 var isEven = require( '@stdlib/assert/is-even' ).isPrimitive;
    171 var inmap = require( '@stdlib/utils/inmap' );
    172 
    173 var bool;
    174 var arr;
    175 var out;
    176 var i;
    177 
    178 function scale( value, index, collection ) {
    179     if ( isEven( index ) ) {
    180         collection.shift();
    181     } else {
    182         collection.push( index+1 );
    183     }
    184     return value * index;
    185 }
    186 
    187 arr = new Array( 100 );
    188 for ( i = 0; i < arr.length; i++ ) {
    189     arr[ i ] = i;
    190 }
    191 out = inmap( arr, scale );
    192 
    193 bool = ( out === arr );
    194 console.log( bool );
    195 
    196 console.log( out );
    197 ```
    198 
    199 </section>
    200 
    201 <!-- /.examples -->
    202 
    203 <!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
    204 
    205 <section class="references">
    206 
    207 </section>
    208 
    209 <!-- /.references -->
    210 
    211 <!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
    212 
    213 <section class="links">
    214 
    215 [mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
    216 
    217 [mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
    218 
    219 [mdn-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object
    220 
    221 [mdn-array-map]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map
    222 
    223 </section>
    224 
    225 <!-- /.links -->