time-to-botec

Benchmark sampling in different programming languages
Log | Files | Refs | README

README.md (4026B)

      1 <!--
      2 
      3 @license Apache-2.0
      4 
      5 Copyright (c) 2020 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 # mediansorted
     22 
     23 > Calculate the median value of a sorted strided array.
     24 
     25 <section class="intro">
     26 
     27 </section>
     28 
     29 <!-- /.intro -->
     30 
     31 <section class="usage">
     32 
     33 ## Usage
     34 
     35 ```javascript
     36 var mediansorted = require( '@stdlib/stats/base/mediansorted' );
     37 ```
     38 
     39 #### mediansorted( N, x, stride )
     40 
     41 Computes the median value of a sorted strided array `x`.
     42 
     43 ```javascript
     44 var x = [ 1.0, 2.0, 3.0 ];
     45 var v = mediansorted( x.length, x, 1 );
     46 // returns 2.0
     47 
     48 x = [ 3.0, 2.0, 1.0 ];
     49 v = mediansorted( x.length, x, 1 );
     50 // returns 2.0
     51 ```
     52 
     53 The function has the following parameters:
     54 
     55 -   **N**: number of indexed elements.
     56 -   **x**: input [`Array`][mdn-array] or [`typed array`][mdn-typed-array].
     57 -   **stride**: index increment for `x`.
     58 
     59 The `N` and `stride` parameters determine which elements in `x` are accessed at runtime. For example, to compute the median value of every other element in `x`,
     60 
     61 ```javascript
     62 var floor = require( '@stdlib/math/base/special/floor' );
     63 
     64 var x = [ 1.0, 2.0, 2.0, -7.0, 3.0, 3.0, 4.0, 2.0 ];
     65 var N = floor( x.length / 2 );
     66 
     67 var v = mediansorted( N, x, 2 );
     68 // returns 2.5
     69 ```
     70 
     71 Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.
     72 
     73 <!-- eslint-disable stdlib/capitalized-comments -->
     74 
     75 ```javascript
     76 var Float64Array = require( '@stdlib/array/float64' );
     77 var floor = require( '@stdlib/math/base/special/floor' );
     78 
     79 var x0 = new Float64Array( [ 2.0, 1.0, 2.0, 2.0, -2.0, 2.0, 3.0, 4.0 ] );
     80 var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
     81 
     82 var N = floor( x0.length / 2 );
     83 
     84 var v = mediansorted( N, x1, 2 );
     85 // returns 2.0
     86 ```
     87 
     88 #### mediansorted.ndarray( N, x, stride, offset )
     89 
     90 Computes the median value of a sorted strided array using alternative indexing semantics.
     91 
     92 ```javascript
     93 var x = [ 1.0, 2.0, 3.0 ];
     94 
     95 var v = mediansorted.ndarray( x.length, x, 1, 0 );
     96 // returns 2.0
     97 ```
     98 
     99 The function has the following additional parameters:
    100 
    101 -   **offset**: starting index for `x`.
    102 
    103 While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying `buffer`, the `offset` parameter supports indexing semantics based on a starting index. For example, to calculate the median value for every other value in `x` starting from the second value
    104 
    105 ```javascript
    106 var floor = require( '@stdlib/math/base/special/floor' );
    107 
    108 var x = [ 2.0, 1.0, 2.0, 2.0, -2.0, 2.0, 3.0, 4.0 ];
    109 var N = floor( x.length / 2 );
    110 
    111 var v = mediansorted.ndarray( N, x, 2, 1 );
    112 // returns 2.0
    113 ```
    114 
    115 </section>
    116 
    117 <!-- /.usage -->
    118 
    119 <section class="notes">
    120 
    121 ## Notes
    122 
    123 -   If `N <= 0`, both functions return `NaN`.
    124 -   The input strided array must be sorted in either **strictly** ascending or descending order.
    125 
    126 </section>
    127 
    128 <!-- /.notes -->
    129 
    130 <section class="examples">
    131 
    132 ## Examples
    133 
    134 <!-- eslint no-undef: "error" -->
    135 
    136 ```javascript
    137 var Float64Array = require( '@stdlib/array/float64' );
    138 var mediansorted = require( '@stdlib/stats/base/mediansorted' );
    139 
    140 var x;
    141 var i;
    142 
    143 x = new Float64Array( 10 );
    144 for ( i = 0; i < x.length; i++ ) {
    145     x[ i ] = i - 5.0;
    146 }
    147 console.log( x );
    148 
    149 var v = mediansorted( x.length, x, 1 );
    150 console.log( v );
    151 ```
    152 
    153 </section>
    154 
    155 <!-- /.examples -->
    156 
    157 <section class="links">
    158 
    159 [mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
    160 
    161 [mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
    162 
    163 </section>
    164 
    165 <!-- /.links -->