Feature/incrwmean

lib/node_modules/@stdlib/stats/incr/wmean/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2019 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.
+
+-->
+
+# incrwmean
+
+> Compute a [weighted arithmetic mean][weighted-arithmetic-mean] incrementally.
+
+<section class="intro">
+
+The [weighted arithmetic mean][weighted-arithmetic-mean] is defined as
+
+<!-- <equation class="equation" label="eq:weighted_arithmetic_mean" align="center" raw="\bar {x}= \frac{\sum_{i=1}^{n} w_{i}x_{i}}{\sum_{i=1}^{n}w_{i}}" alt="Equation for the weighted arithmetic mean."> -->
+
+<div class="equation" align="center" data-raw-text="\bar {x}= \frac{\sum_{i=1}^{n} w_{i}x_{i}}{\sum_{i=1}^{n}w_{i}}" data-equation="eq:weighted_arithmetic_mean">
+    <img src="" alt="Equation for the weighted arithmetic mean.">
+    <br>
+</div>
+
+<!-- </equation> -->
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var incrwmean = require( '@stdlib/stats/incr/wmean' );
+```
+
+#### incrwmean()
+
+Returns an accumulator `function` which incrementally computes a [weighted arithmetic mean][weighted-arithmetic-mean].
+
+```javascript
+var accumulator = incrwmean();
+```
+
+#### accumulator( \[x, w] )
+
+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.
+
+```javascript
+var accumulator = incrwmean();
+
+var mu = accumulator( 2.0, 1.0 );
+// returns 2.0
+
+mu = accumulator( 2.0, 0.5 );
+// returns 2.0
+
+mu = accumulator( 3.0, 1.5 );
+// returns 2.5
+
+mu = accumulator();
+// returns 2.5
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   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.
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var randu = require( '@stdlib/random/base/randu' );
+var incrwmean = require( '@stdlib/stats/incr/wmean' );
+
+var accumulator;
+var v;
+var w;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrwmean();
+
+// For each simulated datum, update the weighted mean...
+for ( i = 0; i < 100; i++ ) {
+    v = randu() * 100.0;
+    w = randu() * 100.0;
+    accumulator( v, w );
+}
+console.log( accumulator() );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<section class="links">
+
+[weighted-arithmetic-mean]: https://en.wikipedia.org/wiki/Weighted_arithmetic_mean
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/stats/incr/wmean/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2019 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 bench = require( '@stdlib/bench' );
+var randu = require( '@stdlib/random/base/randu' );
+var pkg = require( './../package.json' ).name;
+var incrwmean = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var f;
+	var i;
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		f = incrwmean();
+		if ( typeof f !== 'function' ) {
+			b.fail( 'should return a function' );
+		}
+	}
+	b.toc();
+	if ( typeof f !== 'function' ) {
+		b.fail( 'should return a function' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::accumulator', function benchmark( b ) {
+	var acc;
+	var v;
+	var i;
+
+	acc = incrwmean();
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = acc( randu(), randu() );
+		if ( v !== v ) {
+			b.fail( 'should not return NaN' );
+		}
+	}
+	b.toc();
+	if ( v !== v ) {
+		b.fail( 'should not return NaN' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});

lib/node_modules/@stdlib/stats/incr/wmean/docs/repl.txt

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+
+{{alias}}()
+    Returns an accumulator function which incrementally computes a weighted
+    arithmetic mean.
+
+    If provided arguments, the accumulator function returns an updated
+    weighted mean. If not provided arguments, the accumulator function returns
+    the current weighted mean.
+
+    If provided `NaN` or a value which, when used in computations, results in
+    `NaN`, the accumulated value is `NaN` for all future invocations.
+
+    The accumulator accepts two arguments: the first is the value and the
+    second is the weight.
+
+    Returns
+    -------
+    acc: Function
+        Accumulator function.
+
+    Examples
+    --------
+    > var accumulator = {{alias}}();
+    > var mu = accumulator()
+    null
+    > mu = accumulator( 2.0, 1.0 )
+    2.0
+    > mu = accumulator( 2.0, 0.5 )
+    2.0
+    > mu = accumulator( 3.0, 1.5 )
+    2.5
+    > mu = accumulator()
+    2.5
+
+    See Also
+    --------
+

lib/node_modules/@stdlib/stats/incr/wmean/docs/types/index.d.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2019 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.
+*/
+
+// TypeScript Version: 2.0
+
+/// <reference types="@stdlib/types"/>
+
+/**
+ * Weighted arithmetic mean accumulator function
+ *
+ * @param x value
+ * @param w weight
+ *
+ * @returns the incrementally computed weighted arithmetic mean.
+ *
+ */
+type incrwmean_acc = ( x: number, w: number ) => number | null;
+
+/**
+* Returns an accumulator function which incrementally computes a weighted arithmetic mean.
+*
+* @returns accumulator function
+*
+* @example
+* var incrwmean = require( '@stdlib/stats/incr/wmean' );
+*
+* var accumulator = incrwmean();
+*
+* var mu = accumulator();
+* // returns null
+*
+* var mu = accumulator( 2.0, 1.0 );
+* // returns 2.0
+*
+* mu = accumulator( 2.0, 0.5 );
+* // returns 2.0
+*
+* mu = accumulator( 3.0, 1.5 );
+* // returns 2.5
+*
+* mu = accumulator();
+* // returns 2.5
+*/
+declare function incrwmean(): incrwmean_acc;
+
+
+// EXPORTS //
+
+export = incrwmean;

lib/node_modules/@stdlib/stats/incr/wmean/docs/types/test.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2019 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.
+*/
+
+import incrwmean = require( './index' );
+
+// TESTS //
+
+// The function returns either a number or null...
+{
+	incrwmean(); // $ExpectType incrwmean_acc
+}
+
+// The compiler throws an error if the function is provided arguments...
+{
+	incrwmean( '5' ); // $ExpectError
+	incrwmean( 5 ); // $ExpectError
+	incrwmean( true ); // $ExpectError
+	incrwmean( false ); // $ExpectError
+	incrwmean( null ); // $ExpectError
+	incrwmean( undefined ); // $ExpectError
+	incrwmean( [] ); // $ExpectError
+	incrwmean( {} ); // $ExpectError
+	incrwmean( ( x: number ): number => x ); // $ExpectError
+}
+
+// The compiler throws an error if the function is provided arguments...
+{
+	let acc = incrwmean();
+
+	acc( '5' ); // $ExpectError
+	acc( 5 ); // $ExpectError
+	acc( true ); // $ExpectError
+	acc( false ); // $ExpectError
+	acc( null ); // $ExpectError
+	acc( undefined ); // $ExpectError
+	acc( [] ); // $ExpectError
+	acc( {} ); // $ExpectError
+	acc( ( x: number ): number => x ); // $ExpectError
+}

lib/node_modules/@stdlib/stats/incr/wmean/examples/index.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2019 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';
+
+var randu = require( '@stdlib/random/base/randu' );
+var incrwmean = require( './../lib' );
+
+var accumulator;
+var mu;
+var x;
+var w;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrwmean();
+
+// For each simulated datum, update the weighted mean...
+console.log( '\nValue\tWeight\tWeighted Mean\n' );
+for ( i = 0; i < 100; i++ ) {
+	x = randu() * 100.0;
+	w = randu() * 100.0;
+	mu = accumulator( x );
+	console.log( '%d\t%d\t%d', x.toFixed( 4 ), w.toFixed( 4 ), mu.toFixed( 4 ) );
+}
+console.log( '\nFinal weighted mean: %d\n', accumulator() );