npm package: @stdlib/random-strided-discrete-uniform
Description: Fill a strided array with pseudorandom numbers drawn from a discrete uniform distribution.
Author: The Stdlib Authors
Latest version: 0.2.2

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# Discrete Uniform Random Numbers

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Fill a strided array with pseudorandom numbers drawn from a [discrete uniform][@stdlib/random/base/uniform] distribution.

<section class="installation">

## Installation

```bash
npm install @stdlib/random-strided-discrete-uniform
```

</section>

<section class="usage">

## Usage

```javascript
var discreteUniform = require( '@stdlib/random-strided-discrete-uniform' );
```

#### discreteUniform( N, a, sa, b, sb, out, so\[, options] )

Fills a strided array with pseudorandom numbers drawn from a [discrete uniform][@stdlib/random/base/uniform] distribution.

```javascript
var Int32Array = require( '@stdlib/array-int32' );

// Create an array:
var out = new Int32Array( 10 );

// Fill the array with pseudorandom numbers:
discreteUniform( out.length, [ -10 ], 0, [ 10 ], 0, out, 1 );
```

The function has the following parameters:

-   **N**: number of indexed elements.
-   **a**: minimum support.
-   **sa**: index increment for `a`.
-   **b**: maximum support.
-   **sb**: index increment for `b`.
-   **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 out = [ 0, 0, 0, 0, 0, 0 ];

discreteUniform( 3, [ -10 ], 0, [ 10 ], 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 Int32Array = require( '@stdlib/array-int32' );

// Initial arrays...
var a0 = new Int32Array( [ -10, -10, -10, 0, 0, 0 ] );
var b0 = new Int32Array( [ 10, 10, 10, 10, 10, 10 ] );

// Create offset views...
var a1 = new Int32Array( a0.buffer, a0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var b1 = new Int32Array( b0.buffer, b0.BYTES_PER_ELEMENT*3 ); // start at 4th element

// Create an output array:
var out = new Int32Array( 3 );

// Fill the output array:
discreteUniform( out.length, a1, -2, b1, 1, out, 1 );
```

The function accepts the following `options`:

-   **prng**: pseudorandom number generator for generating uniformly distributed pseudorandom numbers. If provided, the function **ignores** both the `state` and `seed` options. In order to seed the underlying pseudorandom number generator, one must seed the provided `prng` (assuming the provided `prng` is seedable).
-   **seed**: pseudorandom number generator seed.
-   **state**: a [`Uint32Array`][@stdlib/array/uint32] containing pseudorandom number generator state. If provided, the function ignores the `seed` option.
-   **copy**: `boolean` indicating whether to copy a provided pseudorandom number generator state. Setting this option to `false` allows sharing state between two or more pseudorandom number generators. Setting this option to `true` ensures that an underlying generator has exclusive control over its internal state. Default: `true`.

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

```javascript
var Int32Array = require( '@stdlib/array-int32' );
var minstd = require( '@stdlib/random-base-minstd' );

var opts = {
    'prng': minstd
};

var out = new Int32Array( 10 );
discreteUniform( out.length, [ -10 ], 0, [ 10 ], 0, out, 1, opts );
```

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

```javascript
var Int32Array = require( '@stdlib/array-int32' );

var opts = {
    'seed': 12345
};

var out = new Int32Array( 10 );
discreteUniform( out.length, [ -10 ], 0, [ 10 ], 0, out, 1, opts );
```

#### discreteUniform.ndarray( N, a, sa, oa, b, sb, ob, out, so, oo\[, options] )

Fills a strided array with pseudorandom numbers drawn from a [discrete uniform][@stdlib/random/base/uniform] distribution using alternative indexing semantics.

```javascript
var Int32Array = require( '@stdlib/array-int32' );

// Create an array:
var out = new Int32Array( 10 );

// Fill the array with pseudorandom numbers:
discreteUniform.ndarray( out.length, [ -10 ], 0, 0, [ 10 ], 0, 0, out, 1, 0 );
```

The function has the following additional parameters:

-   **oa**: starting index for `a`.
-   **ob**: starting index for `b`.
-   **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 out = [ 0, 0, 0, 0, 0, 0 ];

discreteUniform.ndarray( 3, [ -10 ], 0, 0, [ 10 ], 0, 0, out, 2, 1 );
```

The function accepts the same `options` as documented above for `discreteUniform()`.

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   If `N <= 0`, both functions leave the output array unchanged.
-   Both functions support array-like objects having getter and setter accessors for array element access.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var zeros = require( '@stdlib/array-zeros' );
var zeroTo = require( '@stdlib/array-base-zero-to' );
var logEach = require( '@stdlib/console-log-each' );
var discreteUniform = require( '@stdlib/random-strided-discrete-uniform' );

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

// Create an array:
var x1 = zeros( 10, 'int32' );

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

// Fill the array with pseudorandom numbers:
discreteUniform( x1.length, [ -10 ], 0, [ 10 ], 0, x1, 1, opts );

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

// Fill the array with the same pseudorandom numbers:
discreteUniform( x2.length, [ -10 ], 0, [ 10 ], 0, x2, 1, opts );

// Print the array contents:
logEach( 'x1[%d] = %d; x2[%d] = %d', 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">

* * *

## See Also

-   <span class="package-name">[`@stdlib/random-base/discrete-uniform`][@stdlib/random/base/discrete-uniform]</span><span class="delimiter">: </span><span class="description">discrete uniform distributed pseudorandom numbers.</span>
-   <span class="package-name">[`@stdlib/random-array/discrete-uniform`][@stdlib/random/array/discrete-uniform]</span><span class="delimiter">: </span><span class="description">create an array containing pseudorandom numbers drawn from a discrete uniform distribution.</span>
-   <span class="package-name">[`@stdlib/random-strided/uniform`][@stdlib/random/strided/uniform]</span><span class="delimiter">: </span><span class="description">fill a strided array with pseudorandom numbers drawn from a continuous uniform distribution.</span>

</section>

<!-- /.related -->

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* * *

## Notice

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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].

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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