feat: add array/base/count-if

lib/node_modules/@stdlib/array/base/count-if/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2024 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.
+
+-->
+
+# countIf
+
+> Count the number of elements in an array that satisfy the provided testing function.
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- Package usage documentation. -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var countIf = require( '@stdlib/array/base/count-if' );
+```
+
+#### countIf( x, predicate\[, thisArg] )
+
+Counts the number of elements in an array that satisfy the provided testing function.
+
+```javascript
+var x = [ 0, 1, 0, 1, 2 ];
+
+function predicate( val ) {
+    return ( val % 2 === 0 );
+}
+
+var out = countIf( x, predicate );
+// returns 3
+```
+
+If a `predicate` function returns a truthy value, the function counts that value.
+
+The `predicate` function is provided three arguments:
+
+-   **value**: current array element.
+-   **index**: current array element index.
+-   **arr**: input array.
+
+To set the `predicate` function execution context, provide a `thisArg`.
+
+```javascript
+var x = [ 1, 2, 3, 4 ];
+
+var context = {
+    'target': 3
+};
+
+function predicate( value ) {
+    return ( value > this.target );
+}
+
+var out = countIf( x, predicate, context );
+// returns 1
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var bernoulli = require( '@stdlib/random/array/bernoulli' );
+var countIf = require( '@stdlib/array/base/count-if' );
+
+var x = bernoulli( 100, 0.5, {
+    'dtype': 'generic'
+});
+console.log( x );
+
+function predicate( val ) {
+    return val === 1;
+}
+var n = countIf( x, predicate );
+console.log( n );
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- 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/array/base/count-if/benchmark/benchmark.length.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 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 pow = require( '@stdlib/math/base/special/pow' );
+var isNonNegativeInteger = require( '@stdlib/assert/is-nonnegative-integer' ).isPrimitive;
+var bernoulli = require( '@stdlib/random/array/bernoulli' );
+var pkg = require( './../package.json' ).name;
+var countIf = require( './../lib' );
+
+
+// FUNCTIONS //
+
+/**
+* Creates a benchmark function.
+*
+* @private
+* @param {PositiveInteger} len - array length
+* @returns {Function} benchmark function
+*/
+function createBenchmark( len ) {
+	var x = bernoulli( len, 0.5, {
+		'dtype': 'generic'
+	});
+	return benchmark;
+
+	/**
+	* Benchmark function.
+	*
+	* @private
+	* @param {Benchmark} b - benchmark instance
+	*/
+	function benchmark( b ) {
+		var out;
+		var i;
+
+		b.tic();
+		for ( i = 0; i < b.iterations; i++ ) {
+			out = countIf( x, function predicate( v ) {
+				return v === 1;
+			} );
+			if ( typeof out !== 'number' ) {
+				b.fail( 'should return a number' );
+			}
+		}
+		b.toc();
+		if ( !isNonNegativeInteger( out ) ) {
+			b.fail( 'should return a nonnegative integer' );
+		}
+		b.pass( 'benchmark finished' );
+		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( pkg+':dtype=generic,len='+len, f );
+	}
+}
+
+main();

lib/node_modules/@stdlib/array/base/count-if/docs/repl.txt

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+
+{{alias}}( x, predicate[, thisArg] )
+    Counts the number of elements in an array that satisfy the provided testing 
+    function.
+
+    Parameters
+    ----------
+    x: ArrayLikeObject
+        Input array.
+
+    predicate: Function
+        Testing function.
+
+    thisArg: any (optional)
+        Execution context.
+
+    Returns
+    -------
+    out: integer
+        Number of truthy values for which the testing function evaluates to 
+        true.
+
+    Examples
+    --------
+    > var out = {{alias}}( [ 0, 1, 1 ], function predicate( v ) {
+    ...     return v === 1;
+    ... } )
+    2
+
+    See Also
+    --------
+

lib/node_modules/@stdlib/array/base/count-if/docs/types/index.d.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2024 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 { Collection, AccessorArrayLike } from '@stdlib/types/array';
+
+/**
+* Returns a boolean indicating whether an element passes a test.
+*
+* @returns boolean indicating whether an element passes a test
+*/
+type Nullary<U> = ( this: U ) => boolean;
+
+/**
+* Returns a boolean indicating whether an element passes a test.
+*
+* @param value - current array element
+* @returns boolean indicating whether an element passes a test
+*/
+type Unary<T, U> = ( this: U, value: T ) => boolean;
+
+/**
+* Returns a boolean indicating whether an element passes a test.
+*
+* @param value - current array element
+* @param index - current array element index
+* @returns boolean indicating whether an element passes a test
+*/
+type Binary<T, U> = ( this: U, value: T, index: number ) => boolean;
+
+/**
+* Returns a boolean indicating whether an element passes a test.
+*
+* @param value - current array element
+* @param index - current array element index
+* @param arr - input array
+* @returns boolean indicating whether an element passes a test
+*/
+type Ternary<T, U> = ( this: U, value: T, index: number, arr: Collection<T> | AccessorArrayLike<T> ) => boolean;
+
+/**
+* Returns a boolean indicating whether an element passes a test.
+*
+* @param value - current array element
+* @param index - current array element index
+* @param arr - input array
+* @returns boolean indicating whether an element passes a test
+*/
+type Predicate<T, U> = Nullary<U> | Unary<T, U> | Binary<T, U> | Ternary<T, U>;
+
+/**
+* Counts the number of truthy values in an array.
+*
+* @param x - input array
+* @param predicate - testing function
+* @param thisArg - function context
+* @returns number of values for which the provided function evaluates to true
+*
+* @example
+* var x = [ 0, 1, 0, 1 ];
+* function predicate( v ) {
+*     return v > this;
+* }
+* var n = countIf( x, predicate, 0 );
+* // returns 2
+*/
+declare function countIf<T = unknown, U = unknown>( x: Collection<T> | AccessorArrayLike<T>, predicate: Predicate<T, U>, thisArg?: ThisParameterType<Predicate<T, U>> ): number;
+
+
+// EXPORTS //
+
+export = countIf;