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55 changes: 24 additions & 31 deletions lib/node_modules/@stdlib/stats/base/nanmeanwd/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,7 @@ The [arithmetic mean][arithmetic-mean] is defined as
var nanmeanwd = require( '@stdlib/stats/base/nanmeanwd' );
```

#### nanmeanwd( N, x, stride )
#### nanmeanwd( N, x, strideX )

Computes the [arithmetic mean][arithmetic-mean] of a strided array `x`, ignoring `NaN` values and using Welford's algorithm.

Expand All @@ -67,38 +67,32 @@ The function has the following parameters:

- **N**: number of indexed elements.
- **x**: input [`Array`][mdn-array] or [`typed array`][mdn-typed-array].
- **stride**: index increment for `x`.
- **strideX**: stride length for `x`.

The `N` and `stride` parameters determine which elements in `x` are accessed at runtime. For example, to compute the [arithmetic mean][arithmetic-mean] of every other element in `x`,
The `N` and stride parameters determine which elements in the strided array are accessed at runtime. For example, to compute the [arithmetic mean][arithmetic-mean] of every other element in `x`,

```javascript
var floor = require( '@stdlib/math/base/special/floor' );

var x = [ 1.0, 2.0, 2.0, -7.0, -2.0, 3.0, 4.0, 2.0, NaN ];
var N = floor( x.length / 2 );

var v = nanmeanwd( N, x, 2 );
var v = nanmeanwd( 5, x, 2 );
// returns 1.25
```

Note that indexing is relative to the first index. To introduce an offset, use [`typed array`][mdn-typed-array] views.

<!-- eslint-disable stdlib/capitalized-comments -->
<!-- eslint-disable stdlib/capitalized-comments, max-len -->

```javascript
var Float64Array = require( '@stdlib/array/float64' );
var floor = require( '@stdlib/math/base/special/floor' );

var x0 = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN ] );
var x0 = new Float64Array( [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN, NaN ] );
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var N = floor( x0.length / 2 );

var v = nanmeanwd( N, x1, 2 );
var v = nanmeanwd( 5, x1, 2 );
// returns 1.25
```

#### nanmeanwd.ndarray( N, x, stride, offset )
#### nanmeanwd.ndarray( N, x, strideX, offsetX )

Computes the [arithmetic mean][arithmetic-mean] of a strided array, ignoring `NaN` values and using Welford's algorithm and alternative indexing semantics.

Expand All @@ -112,17 +106,16 @@ var v = nanmeanwd.ndarray( N, x, 1, 0 );

The function has the following additional parameters:

- **offset**: starting index for `x`.
- **offsetX**: starting index for `x`.

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 [arithmetic mean][arithmetic-mean] for every other value in `x` starting from the second value
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 [arithmetic mean][arithmetic-mean] for every other element in the strided array starting from the second element

```javascript
var floor = require( '@stdlib/math/base/special/floor' );

var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN ];
var N = floor( x.length / 2 );
var x = [ 2.0, 1.0, 2.0, -2.0, -2.0, 2.0, 3.0, 4.0, NaN, NaN ];

var v = nanmeanwd.ndarray( N, x, 2, 1 );
var v = nanmeanwd.ndarray( 5, x, 2, 1 );
// returns 1.25
```

Expand All @@ -135,6 +128,7 @@ var v = nanmeanwd.ndarray( N, x, 2, 1 );
## Notes

- If `N <= 0`, both functions return `NaN`.
- - Both functions support array-like objects having getter and setter accessors for array element access (e.g., [`@stdlib/array/base/accessor`][@stdlib/array/base/accessor]).
- If every indexed element is `NaN`, both functions return `NaN`.
- Depending on the environment, the typed versions ([`dnanmeanwd`][@stdlib/stats/base/dnanmeanwd], [`snanmeanwd`][@stdlib/stats/base/snanmeanwd], etc.) are likely to be significantly more performant.

Expand All @@ -149,22 +143,19 @@ var v = nanmeanwd.ndarray( N, x, 2, 1 );
<!-- eslint no-undef: "error" -->

```javascript
var randu = require( '@stdlib/random/base/randu' );
var round = require( '@stdlib/math/base/special/round' );
var Float64Array = require( '@stdlib/array/float64' );
var uniform = require( '@stdlib/random/base/uniform' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var nanmeanwd = require( '@stdlib/stats/base/nanmeanwd' );
var bernoulli = require( '@stdlib/random/base/bernoulli' );

var x;
var i;

x = new Float64Array( 10 );
for ( i = 0; i < x.length; i++ ) {
if ( randu() < 0.2 ) {
x[ i ] = NaN;
} else {
x[ i ] = round( (randu()*100.0) - 50.0 );
function rand() {
if ( bernoulli( 0.8 ) < 1 ) {
return NaN;
}
return uniform( -50.0, 50.0 );
}

var x = filledarrayBy( 10, 'float64', rand );
console.log( x );

var v = nanmeanwd( x.length, x, 1 );
Expand Down Expand Up @@ -215,6 +206,8 @@ console.log( v );

[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray

[@stdlib/array/base/accessor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/base/accessor

[@welford:1962a]: https://doi.org/10.1080/00401706.1962.10490022

[@vanreeken:1968a]: https://doi.org/10.1145/362929.362961
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -21,15 +21,30 @@
// MODULES //

var bench = require( '@stdlib/bench' );
var randu = require( '@stdlib/random/base/randu' );
var uniform = require( '@stdlib/random/base/uniform' );
var bernoulli = require( '@stdlib/random/base/bernoulli' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var pkg = require( './../package.json' ).name;
var nanmeanwd = require( './../lib/nanmeanwd.js' );
var nanmeanwd = require( './../lib/main.js' );


// FUNCTIONS //

/**
* Returns a random value or `NaN`.
*
* @private
* @returns {number} random number or `NaN`
*/
function rand() {
if ( bernoulli( 0.8 ) < 1 ) {
return NaN;
}
return uniform( -10.0, 10.0 );
}

/**
* Creates a benchmark function.
*
Expand All @@ -38,17 +53,7 @@ var nanmeanwd = require( './../lib/nanmeanwd.js' );
* @returns {Function} benchmark function
*/
function createBenchmark( len ) {
var x;
var i;

x = [];
for ( i = 0; i < len; i++ ) {
if ( randu() < 0.2 ) {
x.push( NaN );
} else {
x.push( ( randu()*20.0 ) - 10.0 );
}
}
var x = filledarrayBy( len, 'float64', rand );
return benchmark;

function benchmark( b ) {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,9 @@
// MODULES //

var bench = require( '@stdlib/bench' );
var randu = require( '@stdlib/random/base/randu' );
var uniform = require( '@stdlib/random/base/uniform' );
var bernoulli = require( '@stdlib/random/base/bernoulli' );
var filledarrayBy = require( '@stdlib/array/filled-by' );
var isnan = require( '@stdlib/math/base/assert/is-nan' );
var pow = require( '@stdlib/math/base/special/pow' );
var pkg = require( './../package.json' ).name;
Expand All @@ -30,6 +32,19 @@ var nanmeanwd = require( './../lib/ndarray.js' );

// FUNCTIONS //

/**
* Returns a random value or `NaN`.
*
* @private
* @returns {number} random number or `NaN`
*/
function rand() {
if ( bernoulli( 0.8 ) < 1 ) {
return NaN;
}
return uniform( -10.0, 10.0 );
}

/**
* Creates a benchmark function.
*
Expand All @@ -38,17 +53,7 @@ var nanmeanwd = require( './../lib/ndarray.js' );
* @returns {Function} benchmark function
*/
function createBenchmark( len ) {
var x;
var i;

x = [];
for ( i = 0; i < len; i++ ) {
if ( randu() < 0.2 ) {
x.push( NaN );
} else {
x.push( ( randu()*20.0 ) - 10.0 );
}
}
var x = filledarrayBy( len, 'float64', rand );
return benchmark;

function benchmark( b ) {
Expand Down
34 changes: 15 additions & 19 deletions lib/node_modules/@stdlib/stats/base/nanmeanwd/docs/repl.txt
Original file line number Diff line number Diff line change
@@ -1,10 +1,10 @@

{{alias}}( N, x, stride )
{{alias}}( N, x, strideX )
Computes the arithmetic mean of a strided array, ignoring `NaN` values and
using Welford's algorithm.

The `N` and `stride` parameters determine which elements in `x` are accessed
at runtime.
The `N` and `stride` parameters determine which elements
in the strided array are accessed at runtime.

Indexing is relative to the first index. To introduce an offset, use a typed
array view.
Expand All @@ -21,8 +21,8 @@
x: Array<number>|TypedArray
Input array.

stride: integer
Index increment.
strideX: integer
Stride length.

Returns
-------
Expand All @@ -38,20 +38,17 @@

// Using `N` and `stride` parameters:
> x = [ -2.0, 1.0, 1.0, -5.0, 2.0, -1.0, NaN ];
> var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 );
> var stride = 2;
> {{alias}}( N, x, stride )
> {{alias}}( 4, x, 2 )
~0.3333

// Using view offsets:
> var x0 = new {{alias:@stdlib/array/float64}}( [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0, NaN ] );
> var x0 = new {{alias:@stdlib/array/float64}}( [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0, NaN, NaN ] );
> var x1 = new {{alias:@stdlib/array/float64}}( x0.buffer, x0.BYTES_PER_ELEMENT*1 );
> N = {{alias:@stdlib/math/base/special/floor}}( x0.length / 2 );
> stride = 2;
> {{alias}}( N, x1, stride )
> {{alias}}( 4, x1, 2 )
~-0.3333

{{alias}}.ndarray( N, x, stride, offset )

{{alias}}.ndarray( N, x, strideX, offsetX )
Computes the arithmetic mean of a strided array, ignoring `NaN` values and
using Welford's algorithm and alternative indexing semantics.

Expand All @@ -67,10 +64,10 @@
x: Array<number>|TypedArray
Input array.

stride: integer
Index increment.
strideX: integer
Stride length.

offset: integer
offsetX: integer
Starting index.

Returns
Expand All @@ -86,9 +83,8 @@
~0.3333

// Using offset parameter:
> var x = [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0, NaN ];
> var N = {{alias:@stdlib/math/base/special/floor}}( x.length / 2 );
> {{alias}}.ndarray( N, x, 2, 1 )
> var x = [ 1.0, -2.0, 3.0, 2.0, 5.0, -1.0, NaN, NaN ];
> {{alias}}.ndarray( 4, x, 2, 1 )
~-0.3333

See Also
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,12 @@

/// <reference types="@stdlib/types"/>

import { NumericArray } from '@stdlib/types/array';
import { NumericArray, Collection, AccessorArrayLike } from '@stdlib/types/array';

/**
* Input array.
*/
type InputArray = NumericArray | Collection<number> | AccessorArrayLike<number>;

/**
* Interface describing `nanmeanwd`.
Expand All @@ -31,7 +36,7 @@ interface Routine {
*
* @param N - number of indexed elements
* @param x - input array
* @param stride - stride length
* @param strideX - stride length
* @returns arithmetic mean
*
* @example
Expand All @@ -40,7 +45,7 @@ interface Routine {
* var v = nanmeanwd( x.length, x, 1 );
* // returns ~0.3333
*/
( N: number, x: NumericArray, stride: number ): number;
( N: number, x: InputArray, strideX: number ): number;

/**
* Computes the arithmetic mean of a strided array, ignoring `NaN` values and using Welford's algorithm and alternative indexing semantics.
Expand All @@ -57,15 +62,15 @@ interface Routine {
* var v = nanmeanwd.ndarray( x.length, x, 1, 0 );
* // returns ~0.3333
*/
ndarray( N: number, x: NumericArray, stride: number, offset: number ): number;
ndarray( N: number, x: InputArray, strideX: number, offset: number ): number;
}

/**
* Computes the arithmetic mean of a strided array, ignoring `NaN` values and using Welford's algorithm.
*
* @param N - number of indexed elements
* @param x - input array
* @param stride - stride length
* @param strideX - stride length
* @returns arithmetic mean
*
* @example
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
* limitations under the License.
*/

import AccessorArray = require( '@stdlib/array/base/accessor' );
import nanmeanwd = require( './index' );


Expand All @@ -26,6 +27,8 @@ import nanmeanwd = require( './index' );
const x = new Float64Array( 10 );

nanmeanwd( x.length, x, 1 ); // $ExpectType number
nanmeanwd( x.length, new AccessorArray( x ), 1 ); // $ExpectType number

}

// The compiler throws an error if the function is provided a first argument which is not a number...
Expand Down Expand Up @@ -85,6 +88,8 @@ import nanmeanwd = require( './index' );
const x = new Float64Array( 10 );

nanmeanwd.ndarray( x.length, x, 1, 0 ); // $ExpectType number
nanmeanwd.ndarray( x.length, new AccessorArray( x ), 1, 0 ); // $ExpectType number

}

// The compiler throws an error if the `ndarray` method is provided a first argument which is not a number...
Expand Down
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