Test whether at least
nelements along one or morendarraydimensions pass a test implemented by a predicate function.
var someBy = require( '@stdlib/ndarray/some-by' );Tests whether at least n elements along one or more ndarray dimensions pass a test implemented by a predicate function.
var array = require( '@stdlib/ndarray/array' );
function predicate( value ) {
return value > 0.0;
}
// 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 = someBy( x, 2, predicate );
// returns <ndarray>
console.log( out.get() );
// => trueThe function accepts the following arguments:
- x: input
ndarray. - n: number of elements which must pass the test implemented by a predicate function. May be either a scalar or an
ndarray. Must be broadcast-compatible with the non-reduced dimensions of inputndarray. Must have an integer data type. - options: function options (optional).
- predicate: predicate function.
- thisArg: predicate execution context (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.
var array = require( '@stdlib/ndarray/array' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
function predicate( value ) {
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
var opts = {
'dims': [ 0, 1 ]
};
// Perform reduction:
var out = someBy( x, 2, opts, predicate );
// returns <ndarray>
var v = ndarray2array( out );
// returns [ true, true ]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.
var array = require( '@stdlib/ndarray/array' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
function predicate( value ) {
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
var opts = {
'dims': [ 0, 1 ],
'keepdims': true
};
// Perform reduction:
var out = someBy( x, 2, opts, predicate );
// returns <ndarray>
var v = ndarray2array( out );
// returns [ [ [ true, true ] ] ]To set the predicate function execution context, provide a thisArg.
var array = require( '@stdlib/ndarray/array' );
function predicate( value ) {
this.count += 1;
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ [ 1.0, 2.0 ] ], [ [ 3.0, 4.0 ] ], [ [ 0.0, 6.0 ] ] ] );
// returns <ndarray>
// Create a context object:
var ctx = {
'count': 0
};
// Perform operation:
var out = someBy( x, 2, predicate, ctx );
// returns <ndarray>
var v = out.get();
// returns true
var count = ctx.count;
// returns 2Tests whether at least n elements along one or more ndarray dimensions pass a test implemented by a predicate function and assigns results to a provided output ndarray.
var array = require( '@stdlib/ndarray/array' );
var empty = require( '@stdlib/ndarray/empty' );
function predicate( value ) {
return value > 0.0;
}
// 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': 'bool'
});
// Perform reduction:
var out = someBy.assign( x, 2, y, predicate );
// returns <ndarray>
var bool = ( out === y );
// returns true
var v = y.get();
// returns trueThe function accepts the following arguments:
- x: input
ndarray. - n: number of elements which must pass the test implemented by a predicate function. May be either a scalar or an
ndarray. Must be broadcast-compatible with the non-reduced dimensions of inputndarray. Must have an integer data type. - out: output
ndarray. The outputndarraymust have a shape matching the non-reduced dimensions of the inputndarray. - options: function options (optional).
- predicate: predicate function.
- thisArg: predicate execution context (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.
var array = require( '@stdlib/ndarray/array' );
var empty = require( '@stdlib/ndarray/empty' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
function predicate( value ) {
return value > 0.0;
}
// 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( [ 2 ], {
'dtype': 'bool'
});
var opts = {
'dims': [ 0, 1 ]
};
// Perform reduction:
var out = someBy.assign( x, 2, y, opts, predicate );
var bool = ( out === y );
// returns true
var v = ndarray2array( y );
// returns [ true, true ]-
The predicate function is provided the following arguments:
- value: current array element.
- indices: current array element indices.
- arr: the input ndarray.
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var isEven = require( '@stdlib/assert/is-even' ).isPrimitive;
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
var fillBy = require( '@stdlib/ndarray/fill-by' );
var zeros = require( '@stdlib/ndarray/zeros' );
var someBy = require( '@stdlib/ndarray/some-by' );
var x = zeros( [ 2, 4, 5 ], {
'dtype': 'float64'
});
x = fillBy( x, discreteUniform( 0, 10 ) );
console.log( ndarray2array( x ) );
var n = scalar2ndarray( 4, {
'dtype': 'int8'
});
var y = someBy( x, n, isEven );
console.log( y.get() );