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Test whether at least
nelements in an ndarray pass a test implemented by a predicate function.
To use in Observable,
someBy = require( 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-some-by@umd/browser.js' )To vendor stdlib functionality and avoid installing dependency trees for Node.js, you can use the UMD server build:
var someBy = require( 'path/to/vendor/umd/ndarray-base-some-by/index.js' )To include the bundle in a webpage,
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-some-by@umd/browser.js"></script>If no recognized module system is present, access bundle contents via the global scope:
<script type="text/javascript">
(function () {
window.someBy;
})();
</script>Tests whether at least n elements in an ndarray pass a test implemented by a predicate function.
var Float64Array = require( '@stdlib/array-float64' );
var scalar2ndarray = require( '@stdlib/ndarray-from-scalar' );
function predicate( value ) {
return value > 0.0;
}
// Create a data buffer:
var xbuf = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 0.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
// Define the shape of the input array:
var shape = [ 3, 1, 2 ];
// Define the array strides:
var sx = [ 4, 4, 1 ];
// Define the index offset:
var ox = 0;
// Create the input ndarray-like object:
var x = {
'dtype': 'float64',
'data': xbuf,
'shape': shape,
'strides': sx,
'offset': ox,
'order': 'row-major'
};
// Define the success criterion:
var n = scalar2ndarray( 3, {
'dtype': 'generic'
});
// Test elements:
var out = someBy( [ x, n ], predicate );
// returns trueThe function accepts the following arguments:
- arrays: array-like object containing an input ndarray and a zero-dimensional ndarray specifying the minimum number of elements in the input ndarray that must satisfy the predica 8000 te function.
- predicate: predicate function.
- thisArg: predicate function execution context (optional).
Each provided ndarray should be an object with the following properties:
- dtype: data type.
- data: data buffer.
- shape: dimensions.
- strides: stride lengths.
- offset: index offset.
- order: specifies whether an ndarray is row-major (C-style) or column major (Fortran-style).
The predicate function is provided the following arguments:
- value: current array element.
- indices: current array element indices.
- arr: the input ndarray.
To set the predicate function execution context, provide a thisArg.
var Float64Array = require( '@stdlib/array-float64' );
var scalar2ndarray = require( '@stdlib/ndarray-from-scalar' );
function predicate( value ) {
this.count += 1;
return value > 0.0;
}
// Create a data buffer:
var xbuf = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
// Define the shape of the input array:
var shape = [ 3, 1, 2 ];
// Define the array strides:
var sx = [ 4, 4, 1 ];
// Define the index offset:
var ox = 0;
// Create the input ndarray-like object:
var x = {
'dtype': 'float64',
'data': xbuf,
'shape': shape,
'strides': sx,
'offset': ox,
'order': 'row-major'
};
// Define the success criterion:
var n = scalar2ndarray( 6, {
'dtype': 'generic'
});
// Create a context object:
var ctx = {
'count': 0
};
// Test elements:
var out = someBy( [ x, n ], predicate, ctx );
// returns true
var count = ctx.count;
// returns 6- For very high-dimensional ndarrays which are non-contiguous, one should consider copying the underlying data to contiguous memory before performing the operation in order to achieve better performance.
<!DOCTYPE html>
<html lang="en">
<body>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/random-array-discrete-uniform@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-from-scalar@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-to-array@umd/browser.js"></script>
<script type="text/javascript" src="https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-some-by@umd/browser.js"></script>
<script type="text/javascript">
(function () {
function predicate( value ) {
return value > 0;
}
var x = {
'dtype': 'generic',
'data': discreteUniform( 10, -2, 10, {
'dtype': 'generic'
}),
'shape': [ 5, 2 ],
'strides': [ 2, 1 ],
'offset': 0,
'order': 'row-major'
};
console.log( ndarray2array( x.data, x.shape, x.strides, x.offset, x.order ) );
var n = scalar2ndarray( 5, {
'dtype': 'generic'
});
var out = someBy( [ x, n ], predicate );
console.log( out );
})();
</script>
</body>
</html>This package is part of stdlib, a standard library for JavaScript and Node.js, 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.
