npm package: @stdlib/random-strided-tools-unary-factory
Description: Create a factory function for filling strided arrays with pseudorandom values drawn from a unary PRNG.
Author: The Stdlib Authors
Latest version: 0.2.3

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# unaryFactory

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> Create a factory function for filling strided arrays with pseudorandom values drawn from a unary PRNG.

<section class="installation">

## Installation

```bash
npm install @stdlib/random-strided-tools-unary-factory
```

</section>

<section class="usage">

## Usage

```javascript
var unaryFactory = require( '@stdlib/random-strided-tools-unary-factory' );
```

#### unaryFactory( prng )

Returns a factory function for filling strided arrays with pseudorandom values drawn from a unary PRNG.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>
```

The function has the following parameters:

-   **prng**: unary pseudorandom number generator.

* * *

#### factory( \[options] )

Returns a function for filling strided arrays with pseudorandom values drawn from a unary PRNG.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>
```

The function has the following parameters:

-   **options**: function options.

The function supports the following options:

-   **prng**: pseudorandom number generator which generates uniformly distributed pseudorandom numbers.
-   **seed**: pseudorandom value generator seed.
-   **state**: pseudorandom value generator state.
-   **copy**: boolean indicating whether to copy a provided pseudorandom value generator state.

To use a custom PRNG as the underlying source of uniformly distributed pseudorandom numbers, set the `prng` option.

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var minstd = require( '@stdlib/random-base-minstd' );
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var opts = {
    'prng': minstd.normalized
};

var random = factory( opts );
// returns <Function>

var out = new Float64Array( 10 );
random( out.length, [ 2.0 ], 0, out, 1 );
```

To seed the underlying pseudorandom number generator, set the `seed` option.

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var opts = {
    'seed': 12345
};

var random = factory( opts );
// returns <Function>

var out = new Float64Array( 10 );
random( out.length, [ 2.0 ], 0, out, 1 );
```

* * *

#### random( N, param1, sp1, out, so )

Fills a strided array with pseudorandom values drawn from a unary PRNG.

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var out = new Float64Array( 10 );
// returns <Float64Array>

var v = random( out.length, [ 2.0 ], 0, out, 1 );
// returns <Float64Array>
```

The function has the following parameters:

-   **N**: number of indexed elements.
-   **param1**: PRNG parameter.
-   **sp1**: index increment for `param1`.
-   **out**: output array.
-   **so**: index increment for `out`.

The `N` and stride parameters determine which strided array elements are accessed at runtime. For example, to access every other value in `out`,

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

random( 3, [ 2.0 ], 0, out, 2 );
```

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 -->

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

// Initial array:
var param0 = new Float64Array( [ 5.0, 5.0, 5.0, 5.0, 5.0, 5.0 ] );

// Create offset view:
var param1 = new Float64Array( param0.buffer, param0.BYTES_PER_ELEMENT*3 ); // start at 4th element

// Create an output array:
var out = new Float64Array( 3 );

// Fill the output array:
random( out.length, param1, -1, out, 1 );
```

#### random.ndarray( N, param1, sp1, op1, out, so, oo )

Fills a strided array with pseudorandom values drawn from a unary PRNG using alternative indexing semantics.

```javascript
var Float64Array = require( '@stdlib/array-float64' );
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var out = new Float64Array( 10 );
// returns <Float64Array>

var v = random.ndarray( out.length, [ 2.0 ], 0, 0, out, 1, 0 );
// returns <Float64Array>
```

The function has the following additional parameters:

-   **op1**: starting index for `param1`.
-   **oo**: starting index for `out`.

While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying `buffer`, the offset parameters support indexing semantics based on starting indices. For example, to access every other value in `out` starting from the second value,

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var out = [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 ];

random.ndarray( 3, [ 2.0 ], 0, 0, out, 2, 1 );
```

* * *

#### random.PRNG

The underlying pseudorandom number generator.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var prng = random.PRNG;
// returns <Function>
```

#### random.seed

The value used to seed the underlying pseudorandom number generator.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var seed = random.seed;
// returns <Uint32Array>
```

If the `factory` function is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.

```javascript
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory({
    'prng': minstd
});
// returns <Function>

var seed = random.seed;
// returns null
```

#### random.seedLength

Length of underlying pseudorandom number generator seed.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var len = random.seedLength;
// returns <number>
```

If the `factory` function is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.

```javascript
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory({
    'prng': minstd
});
// returns <Function>

var len = random.seedLength;
// returns null
```

#### random.state

Writable property for getting and setting the underlying pseudorandom number generator state.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var state = random.state;
// returns <Uint32Array>
```

If the `factory` function is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.

```javascript
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory({
    'prng': minstd
});
// returns <Function>

var state = random.state;
// returns null
```

#### random.stateLength

Length of underlying pseudorandom number generator state.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var len = random.stateLength;
// returns <number>
```

If the `factory` function is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.

```javascript
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory({
    'prng': minstd
});
// returns <Function>

var len = random.stateLength;
// returns null
```

#### random.byteLength

Size (in bytes) of underlying pseudorandom number generator state.

```javascript
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory();
// returns <Function>

var sz = random.byteLength;
// returns <number>
```

If the `factory` function is provided a PRNG for uniformly distributed numbers, the associated property value on the returned function is `null`.

```javascript
var minstd = require( '@stdlib/random-base-minstd-shuffle' ).normalized;
var exponential = require( '@stdlib/random-base-exponential' );

var factory = unaryFactory( exponential );
// returns <Function>

var random = factory({
    'prng': minstd
});
// returns <Function>

var sz = random.byteLength;
// returns null
```

</section>

<!-- /.usage -->

<section class="notes">

</section>

<!-- /.notes -->

<section class="examples">

* * *

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var exponential = require( '@stdlib/random-base-exponential' );
var zeros = require( '@stdlib/array-zeros' );
var zeroTo = require( '@stdlib/array-zero-to' );
var logEach = require( '@stdlib/console-log-each' );
var unaryFactory = require( '@stdlib/random-strided-tools-unary-factory' );

// Create a PRNG factory function:
var factory = unaryFactory( exponential );
// returns <Function>

// Specify a PRNG seed:
var opts = {
    'seed': 1234
};

// Create a function for filling strided arrays:
var rand1 = factory( opts );
// returns <Function>

// Create an array:
var x1 = zeros( 10, 'float64' );

// Fill the array with pseudorandom numbers:
rand1( x1.length, [ 2.0 ], 0, x1, 1 );

// Create another function for filling strided arrays:
var rand2 = factory( opts );
// returns <Function>

// Create a second array:
var x2 = zeros( 10, 'generic' );

// Fill the array with the same pseudorandom numbers:
rand2( x2.length, [ 2.0 ], 0, x2, 1 );

// Create a list of indices:
var idx = zeroTo( x1.length, 'generic' );

// Print the array contents:
logEach( 'x1[%d] = %.2f; x2[%d] = %.2f', idx, x1, idx, x2 );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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