Test whether a collection contains at least
nelements which pass a test implemented by a predicate function, iterating from right to left.
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var someByRight = require( '@stdlib/utils-some-by-right' );Tests whether a collection contains at least n elements which pass a test implemented by a predicate function, iterating from right to left.
function isNegative( value ) {
return ( value < 0 );
}
var arr = [ -1, 1, -2, 3, 4 ];
var bool = someByRight( arr, 2, isNegative );
// returns trueOnce the function finds n successful elements, the function immediately returns true.
function isNegative( value ) {
if ( value > 0 ) {
throw new Error( 'should never reach this line' );
}
return ( value < 0 );
}
var arr = [ -1, 2, -3, -4 ];
var bool = someByRight( arr, 2, isNegative );
// returns trueThe invoked function is provided three arguments:
value: collection elementindex: collection indexcollection: input collection
To set the function execution context, provide a thisArg.
function sum( value ) {
this.sum += value;
this.count += 1;
return ( value < 0 );
}
var arr = [ -5, 1, 2, 3, 4 ];
var context = {
'sum': 0,
'count': 0
};
var bool = someByRight( arr, 1, sum, context );
// returns true
var mean = context.sum / context.count;
// returns 1.0-
A
collectionmay be either anArray,Typed Array, or an array-likeObject(excludingstringsandfunctions). -
If provided an empty collection, the function returns
false.function alwaysTrue() { return true; } var bool = someByRight( [], 1, alwaysTrue ); // returns false
-
The function does not skip
undefinedelements.function log( value, index ) { console.log( '%s: %s', index, value ); return ( value < 0 ); } var arr = [ -1, 1, , , 4 ]; var bool = someByRight( arr, 1, log ); /* => 4: 4 3: undefined 2: undefined 1: 1 0: -1 */
-
The function provides limited support for dynamic collections (i.e., collections whose
lengthchanges during execution). Note, however, that index incrementation is not guaranteed to be monotonically decreasing.
var randu = require( '@stdlib/random-base-randu' );
var someByRight = require( '@stdlib/utils-some-by-right' );
function threshold( value ) {
return ( value > 0.95 );
}
var bool;
var arr;
var i;
arr = new Array( 100 );
for ( i = 0; i < arr.length; i++ ) {
arr[ i ] = randu();
}
bool = someByRight( arr, 5, threshold );
// returns <boolean>@stdlib/utils/any-by-right: test whether at least one element in a collection passes a test implemented by a predicate function, iterating from right to left.@stdlib/utils/every-by-right: test whether all elements in a collection pass a test implemented by a predicate function, iterating from right to left.@stdlib/utils/for-each-right: invoke a function for each element in a collection, iterating from right to left.@stdlib/utils/none-by-right: test whether all elements in a collection fail a test implemented by a predicate function, iterating from right to left.@stdlib/utils/some-by: test whether a collection contains at leastnelements which pass a test implemented by a predicate function.@stdlib/utils/async/some-by-right: test whether a collection contains at leastnelements which pass a test implemented by a predicate function, iterating from right to left.
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 © 2016-2022. The Stdlib Authors.
