time-to-botec

Benchmark sampling in different programming languages
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README.md (3321B)

      1 <!--
      2 
      3 @license Apache-2.0
      4 
      5 Copyright (c) 2019 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 # incrwmean
     22 
     23 > Compute a [weighted arithmetic mean][weighted-arithmetic-mean] incrementally.
     24 
     25 <section class="intro">
     26 
     27 The [weighted arithmetic mean][weighted-arithmetic-mean] is defined as
     28 
     29 <!-- <equation class="equation" label="eq:weighted_arithmetic_mean" align="center" raw="\bar{x} = \frac{\sum_{i=0}^{n-1} w_{i} x_{i}}{\sum_{i=0}^{n-1} w_{i}}" alt="Equation for the weighted arithmetic mean."> -->
     30 
     31 <div class="equation" align="center" data-raw-text="\bar{x} = \frac{\sum_{i=0}^{n-1} w_{i} x_{i}}{\sum_{i=0}^{n-1} w_{i}}" data-equation="eq:weighted_arithmetic_mean">
     32     <img src="https://cdn.jsdelivr.net/gh/stdlib-js/stdlib@adbea9806383f70c982e3191475c874efba1296b/lib/node_modules/@stdlib/stats/incr/wmean/docs/img/equation_weighted_arithmetic_mean.svg" alt="Equation for the weighted arithmetic mean.">
     33     <br>
     34 </div>
     35 
     36 <!-- </equation> -->
     37 
     38 </section>
     39 
     40 <!-- /.intro -->
     41 
     42 <section class="usage">
     43 
     44 ## Usage
     45 
     46 ```javascript
     47 var incrwmean = require( '@stdlib/stats/incr/wmean' );
     48 ```
     49 
     50 #### incrwmean()
     51 
     52 Returns an accumulator `function` which incrementally computes a [weighted arithmetic mean][weighted-arithmetic-mean].
     53 
     54 ```javascript
     55 var accumulator = incrwmean();
     56 ```
     57 
     58 #### accumulator( \[x, w] )
     59 
     60 If provided an input value `x` and a weight `w`, the accumulator function returns an updated weighted mean. If not provided any input values, the accumulator function returns the current mean.
     61 
     62 ```javascript
     63 var accumulator = incrwmean();
     64 
     65 var mu = accumulator( 2.0, 1.0 );
     66 // returns 2.0
     67 
     68 mu = accumulator( 2.0, 0.5 );
     69 // returns 2.0
     70 
     71 mu = accumulator( 3.0, 1.5 );
     72 // returns 2.5
     73 
     74 mu = accumulator();
     75 // returns 2.5
     76 ```
     77 
     78 </section>
     79 
     80 <!-- /.usage -->
     81 
     82 <section class="notes">
     83 
     84 ## Notes
     85 
     86 -   Input values are **not** type checked. If provided `NaN` or a value which, when used in computations, results in `NaN`, the accumulated value is `NaN` for **all** future invocations. If non-numeric inputs are possible, you are advised to type check and handle accordingly **before** passing the value to the accumulator function.
     87 
     88 </section>
     89 
     90 <!-- /.notes -->
     91 
     92 <section class="examples">
     93 
     94 ## Examples
     95 
     96 <!-- eslint no-undef: "error" -->
     97 
     98 ```javascript
     99 var randu = require( '@stdlib/random/base/randu' );
    100 var incrwmean = require( '@stdlib/stats/incr/wmean' );
    101 
    102 var accumulator;
    103 var v;
    104 var w;
    105 var i;
    106 
    107 // Initialize an accumulator:
    108 accumulator = incrwmean();
    109 
    110 // For each simulated datum, update the weighted mean...
    111 for ( i = 0; i < 100; i++ ) {
    112     v = randu() * 100.0;
    113     w = randu() * 100.0;
    114     accumulator( v, w );
    115 }
    116 console.log( accumulator() );
    117 ```
    118 
    119 </section>
    120 
    121 <!-- /.examples -->
    122 
    123 <section class="links">
    124 
    125 [weighted-arithmetic-mean]: https://en.wikipedia.org/wiki/Weighted_arithmetic_mean
    126 
    127 </section>
    128 
    129 <!-- /.links -->