feat: add stats/base/ndarray/snanvariance

lib/node_modules/@stdlib/stats/base/ndarray/snanvariance/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2026 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.
+
+-->
+
+# snanvariance
+
+> Compute the variance of a one-dimensional single-precision floating-point ndarray, ignoring `NaN` values.
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var snanvariance = require( '@stdlib/stats/base/ndarray/snanvariance' );
+```
+
+#### snanvariance( arrays )
+
+Computes the variance of a one-dimensional single-precision floating-point ndarray, ignoring NaN values.
+
+```javascript
+var Float32Array = require( '@stdlib/array/float32' );
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
+
+var xbuf = new Float32Array( [ 1.0, 3.0, NaN, 2.0 ] );
+var x = new ndarray( 'float32', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
+
+var c = scalar2ndarray( 1.0, {
+    'dtype': 'float32'
+});
+
+var v = snanvariance( [ x, c ] );
+// returns 1.0
+```
+
+The function has the following parameters:
+
+-   **arrays**: array-like object containing two ndarrays:
+    -   **x**: a one-dimensional input ndarray.
+    -   **c**: a zero-dimensional ndarray specifying the degrees of freedom adjustment. Providing a non-zero degrees of freedom adjustment has the effect of adjusting the divisor during the calculation of the variance according to `N-c`, where `N` is the number of non-NaN elements in the input ndarray and `c` corresponds to the provided degrees of freedom adjustment. When computing the variance of a population, setting this parameter to `0` is the standard choice. When computing the corrected sample variance, setting this parameter to `1` is the standard choice (commonly referred to as Bessel's correction).
+
+</section>
+
+<!-- /.usage -->
+
+<section class="notes">
+
+## Notes
+
+-   If provided an empty one-dimensional ndarray, the function returns `NaN`.
+
+</section>
+
+<!-- /.notes -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var uniform = require( '@stdlib/random/base/uniform' );
+var filledarrayBy = require( '@stdlib/array/filled-by' );
+var bernoulli = require( '@stdlib/random/base/bernoulli' );
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
+var snanvariance = require( '@stdlib/stats/base/ndarray/snanvariance' );
+
+function rand() {
+    if ( bernoulli( 0.8 ) < 1 ) {
+        return NaN;
+    }
+    return uniform( -50.0, 50.0 );
+}
+
+var xbuf = filledarrayBy( 10, 'float32', rand );
+var x = new ndarray( 'float32', xbuf, [ xbuf.length ], [ 1 ], 0, 'row-major' );
+
+var c = scalar2ndarray( 1.0, {
+    'dtype': 'float32'
+});
+
+var v = snanvariance( [ x, c ] );
+console.log( v );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/stats/base/ndarray/snanvariance/benchmark/benchmark.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2026 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 uniform = require( '@stdlib/random/base/uniform' );
+var bernoulli = require( '@stdlib/random/base/bernoulli' );
+var filledarrayBy = require( '@stdlib/array/filled-by' );
+var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
+var pow = require( '@stdlib/math/base/special/pow' );
+var ndarray = require( '@stdlib/ndarray/base/ctor' );
+var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
+var format = require( '@stdlib/string/format' );
+var pkg = require( './../package.json' ).name;
+var snanvariance = require( './../lib' );
+
+
+// FUNCTIONS //
+
+/**
+* Returns a random number.
+*
+* @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.
+*
+* @private
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( len ) {
+	var xbuf;
+	var c;
+	var x;
+
+	xbuf = filledarrayBy( len, 'float32', rand );
+	x = new ndarray( 'float32', xbuf, [ len ], [ 1 ], 0, 'row-major' );
+	c = scalar2ndarray( 1.0, {
+		'dtype': 'float32'
+	});
+
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var v;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			v = snanvariance( [ x, c ] );
+		}
+		b.toc();
+
+		// NaN is allowed for variance:
+		if ( isnanf( v ) ) {
+			b.pass( 'returned NaN (allowed)' );
+		} else {
+			b.pass( 'returned a number' );
+		}
+		b.end();
+	}
+}
+
+
+// MAIN //
+
+/**
+* Main execution sequence.
+*
+* @private
+*/
+function main() {
+	var len;
+	var min;
+	var max;
+	var f;
+	var i;
+
+	min = 1; // 10^min
+	max = 6; // 10^max
+
+	for ( i = min; i <= max; i++ ) {
+		len = pow( 10, i );
+		f = createBenchmark( len );
+		bench( format( '%s:len=%d', pkg, len ), f );
+	}
+}
+
+main();

lib/node_modules/@stdlib/stats/base/ndarray/snanvariance/docs/repl.txt

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+
+{{alias}}( arrays )
+    Computes the sample variance of a one-dimensional ndarray, ignoring `NaN`
+    values.
+
+    If the number of non-NaN elements minus the correction is less than or equal
+    to zero, the function returns `NaN`.
+
+    Parameters
+    ----------
+    arrays: ArrayLikeObject<ndarray>
+        Array-like object containing a one-dimensional input ndarray and a
+        zero-dimensional ndarray containing the degrees of freedom adjustment.
+
+    Returns
+    -------
+    out: number
+        Sample variance.
+
+    Examples
+    --------
+    > var xbuf = new {{alias:@stdlib/array/float32}}( [ 1.0, 2.0, NaN, 3.0 ] );
+    > var dt = 'float32';
+    > var sh = [ xbuf.length ];
+    > var sx = [ 1 ];
+    > var ox = 0;
+    > var ord = 'row-major';
+    > var x = new {{alias:@stdlib/ndarray/ctor}}( dt, xbuf, sh, sx, ox, ord );
+    > var c = {{alias:@stdlib/ndarray/from-scalar}}( 1.0, { 'dtype': 'float32' } );
+    > {{alias}}( [ x, c ] )
+    1
+
+    See Also
+    --------
+

lib/node_modules/@stdlib/stats/base/ndarray/snanvariance/docs/types/index.d.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2026 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: 4.1
+
+/// <reference types="@stdlib/types"/>
+
+import { float32ndarray } from '@stdlib/types/ndarray';
+
+/**
+* Computes the variance of a one-dimensional ndarray, ignoring `NaN` values.
+*
+* @param arrays - array-like object containing an input ndarray and a correction ndarray
+* @returns variance
+*
+* @example
+* var Float32Array = require( '@stdlib/array/float32' );
+* var ndarray = require( '@stdlib/ndarray/base/ctor' );
+* var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
+*
+* var xbuf = new Float32Array( [ 1.0, 3.0, NaN, 2.0 ] );
+* var x = new ndarray( 'float32', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
+*
+* var c = scalar2ndarray( 1.0, { 'dtype': 'float32' } );
+*
+* var v = snanvariance( [ x, c ] );
+* // returns 1.0
+*/
+declare function snanvariance(
+	arrays: [ float32ndarray, float32ndarray ]
+): number;
+
+
+// EXPORTS //
+
+export = snanvariance;