feat: add stats/incr/nanvariance function

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

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 incrnanvariance = require( './../lib' );
+
+// MAIN //
+
+bench( pkg, function benchmark( b ) {
+	var f;
+	var i;
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		f = incrnanvariance();
+		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 = incrnanvariance();
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = acc( 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();
+});
+
+bench( pkg+'::accumulator,known_mean', function benchmark( b ) {
+	var acc;
+	var v;
+	var i;
+	acc = incrnanvariance( 3.14 );
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		v = acc( 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/nanvariance/docs/repl.txt

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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.
+*/
+
+{{alias}}( [mean] )
+Returns an accumulator function which incrementally computes an unbiased sample variance, ignoring NaN values.
+
+If provided a value, the accumulator function returns an updated unbiased sample variance. If not provided a value, the accumulator function returns the current unbiased sample variance.
+
+If provided `NaN`, the `NaN` value is ignored and the current accumulated variance is returned.
+
+
+Parameters
+----------
+mean: number (optional)
+    Known mean.
+
+
+Returns
+-------
+acc: Function
+    Accumulator function.
+
+
+Examples
+--------
+> var accumulator = {{alias}}();
+> var s2 = accumulator()
+null
+> s2 = accumulator( 2.0 )
+0.0
+> s2 = accumulator( NaN )
+0.0
+> s2 = accumulator( -5.0 )
+24.5
+> s2 = accumulator()
+24.5
+
+
+See Also
+--------
+@stdlib/stats/incr/variance
+@stdlib/stats/incr/nanstdev

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

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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"/>
+
+/**
+* If provided a value, returns an updated unbiased sample variance; otherwise, returns the current unbiased sample variance.
+*
+* ## Notes
+*
+* -   If provided `NaN`, the `NaN` value is ignored and the current accumulated variance is returned.
+*
+* @param x - value
+* @returns unbiased sample variance
+*/
+type accumulator = ( x?: number ) => number | null;
+
+/**
+* Returns an accumulator function which incrementally computes an unbiased sample variance, ignoring NaN values.
+*
+* @param mu - known mean
+* @returns accumulator function
+*
+* @example
+* var accumulator = incrnanvariance();
+*
+* var s2 = accumulator();
+* // returns null
+*
+* s2 = accumulator( 2.0 );
+* // returns 0.0
+*
+* s2 = accumulator( NaN );
+* // returns 0.0
+*
+* s2 = accumulator( -5.0 );
+* // returns 24.5
+*
+* s2 = accumulator();
+* // returns 24.5
+*/
+declare function incrnanvariance( mu?: number ): accumulator;
+
+
+// EXPORTS //
+
+export = incrnanvariance;

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

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 incrnanvariance from './index' ;
+
+
+// TESTS //
+
+// The function returns an accumulator function...
+{
+	incrnanvariance(); // $ExpectType accumulator
+	incrnanvariance( 0.0 ); // $ExpectType accumulator
+}
+
+// The compiler throws an error if the function is provided invalid arguments...
+{
+	incrnanvariance( '5' as any ); // $ExpectError
+	incrnanvariance( true as any ); // $ExpectError
+	incrnanvariance( false as any ); // $ExpectError
+	incrnanvariance( null as any ); // $ExpectError
+	incrnanvariance( [] as any ); // $ExpectError
+	incrnanvariance( {} as any ); // $ExpectError
+	incrnanvariance( ((x: number): number => x) as any ); // $ExpectError
+}
+
+// The function returns an accumulator function which returns an accumulated result...
+{
+	const acc = incrnanvariance();
+	acc(); // $ExpectType number | null
+	acc( 3.14 ); // $ExpectType number | null
+}
+
+// The compiler throws an error if the returned accumulator function is provided invalid arguments...
+{
+	const acc = incrnanvariance();
+	acc( '5' as any ); // $ExpectError
+	acc( true as any ); // $ExpectError
+	acc( false as any ); // $ExpectError
+	acc( null as any ); // $ExpectError
+	acc( [] as any ); // $ExpectError
+	acc( {} as any ); // $ExpectError
+	acc( ((x: number): number => x) as any ); // $ExpectError
+}

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

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 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 incrnanvariance = require( './../lib' );
+
+var accumulator;
+var s2;
+var v;
+var i;
+
+// Initialize an accumulator:
+accumulator = incrnanvariance();
+
+// For each simulated datum, update the unbiased sample variance...
+console.log( '\nValue\tVariance\n' );
+for ( i = 0; i < 100; i++ ) {
+	if ( randu() < 0.2 ) {
+		v = NaN;
+	} else {
+		v = randu() * 100.0;
+	}
+	s2 = accumulator( v );
+	console.log( '%d\t%d', v, s2 );
+}
+console.log( '\nFinal variance: %d\n', accumulator() );
+
+// Initialize an accumulator with a known mean:
+accumulator = incrnanvariance( 50.0 );
+
+// For each simulated datum, update the unbiased sample variance...
+console.log( '\nValue\tVariance\n' );
+for ( i = 0; i < 100; i++ ) {
+	if ( randu() < 0.2 ) {
+		v = NaN;
+	} else {
+		v = randu() * 100.0;
+	}
+	s2 = accumulator( v );
+	console.log( '%d\t%d', v, s2 );
+}
+console.log( '\nFinal variance: %d\n', accumulator() );