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Count the number of truthy elements along one or more
ndarraydimensions.
import countTruthy from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-count-truthy@deno/mod.js';You can also import the following named exports from the package:
import { assign } from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-count-truthy@deno/mod.js';Counts the number of truthy elements along one or more ndarray dimensions.
import array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-array@deno/mod.js';
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
// Perform reduction:
var out = countTruthy( x );
// returns <ndarray>
var v = out.get();
// returns 5The function accepts the following arguments:
- x: input
ndarray. - options: function options (optional).
The function accepts the following options:
- dims: list of dimensions over which to perform a reduction.
- keepdims: boolean indicating whether the reduced dimensions should be included in the returned
ndarrayas singleton dimensions. Default:false.
By default, the function performs a reduction over all elements in a provided ndarray. To reduce specific dimensions, set the dims option.
import array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-array@deno/mod.js';
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
// Perform reduction:
var out = countTruthy( x, {
'dims': [ 1, 2 ]
});
// returns <ndarray>
var v = ndarray2array( out );
// returns [ 2, 2, 1 ]By default, the function returns an ndarray having a shape matching only the non-reduced dimensions of the input ndarray (i.e., the reduced dimensions are dropped). To include the reduced dimensions as singleton dimensions in the output ndarray, set the keepdims option to true.
import array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-array@deno/mod.js';
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
// Perform reduction:
var out = countTruthy( x, {
'dims': [ 1, 2 ],
'keepdims': true
});
// returns <ndarray>
var v = ndarray2array( out );
// returns [ [ [ 2 ] ], [ [ 2 ] ], [ [ 1 ] ] ]Counts the number of truthy elements along one or more ndarray dimensions and assigns results to a provided output ndarray.
import array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-array@deno/mod.js';
import empty from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-empty@deno/mod.js';
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
// Create an output ndarray:
var y = empty( [], {
'dtype': 'int32'
});
// Perform reduction:
var out = countTruthy.assign( x, y );
// returns <ndarray>
var bool = ( out === y );
// returns true
var v = y.get();
// returns 5The function accepts the following arguments:
- x: input
ndarray. - out: output
ndarray. The outputndarraymust have a shape matching the non-reduced dimensions of the inputndarray. - options: function options (optional).
The function accepts the following options:
- dims: list of dimensions over which to perform a reduction.
By default, the function performs a reduction over all elements in a provided ndarray. To reduce specific dimensions, set the dims option.
import array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-array@deno/mod.js';
import empty from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-empty@deno/mod.js';
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
// Create an output ndarray:
var y = empty( [ 3 ], {
'dtype': 'int32'
});
// Perform reduction:
var out = countTruthy.assign( x, y, {
'dims': [ 1, 2 ]
});
var bool = ( out === y );
// returns true
var v = ndarray2array( y );
// returns [ 2, 2, 1 ]var bernoulli = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/random-base-bernoulli' ).factory;
import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-to-array@deno/mod.js';
import fillBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-fill-by@deno/mod.js';
import zeros from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-zeros@deno/mod.js';
import countTruthy from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-count-truthy@deno/mod.js';
var x = zeros( [ 2, 4, 5 ], {
'dtype': 'float64'
});
x = fillBy( x, bernoulli( 0.90 ) );
console.log( ndarray2array( x ) );
var y = countTruthy( x );
console.log( 'countTruthy(x[:,:,:]) =' );
console.log( y.get() );
y = countTruthy( x, {
'dims': [ 0 ],
'keepdims': true
});
console.log( 'countTruthy(x[:,j,k]) =' );
console.log( ndarray2array( y ) );
y = countTruthy( x, {
'dims': [ 1 ],
'keepdims': true
});
console.log( 'countTruthy(x[i,:,k]) =' );
console.log( ndarray2array( y ) );
y = countTruthy( x, {
'dims': [ 2 ],
'keepdims': true
});
console.log( 'countTruthy(x[i,j,:]) =' );
console.log( ndarray2array( y ) );
y = countTruthy( x, {
'dims': [ 0, 1 ],
'keepdims': true
});
console.log( 'countTruthy(x[:,:,k]) =' );
console.log( ndarray2array( y ) );
y = countTruthy( x, {
'dims': [ 0, 2 ],
'keepdims': true
});
console.log( 'countTruthy(x[:,j,:]) =' );
console.log( ndarray2array( y ) );
y = countTruthy( x, {
'dims': [ 1, 2 ],
'keepdims': true
});
console.log( 'countTruthy(x[i,:,:]) =' );
console.log( ndarray2array( y ) );
y = countTruthy( x, {
'dims': [ 0, 1, 2 ],
'keepdims': true
});
console.log( 'countTruthy(x[:,:,:]) =' );
console.log( ndarray2array( y ) );This package is part of stdlib, a standard library 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, see the main project repository.
See LICENSE.
Copyright © 2016-2025. The Stdlib Authors.
