dmskmin

Calculate the minimum value of a double-precision floating-point strided array according to a mask.

Usage

var dmskmin = require( '@stdlib/stats/base/dmskmin' );

dmskmin( N, x, strideX, mask, strideMask )

Computes the minimum value of a double-precision floating-point strided array according to a mask.

var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );

var x = new Float64Array( [ 1.0, -2.0, -4.0, 2.0 ] );
var mask = new Uint8Array( [ 0, 0, 1, 0 ] );

var v = dmskmin( x.length, x, 1, mask, 1 );
// returns -2.0

The function has the following parameters:

  • N: number of indexed elements.
  • x: input Float64Array.
  • strideX: stride length for x.
  • mask: mask Uint8Array. If a mask array element is 0, the corresponding element in x is considered valid and included in computation. If a mask array element is 1, the corresponding element in x is considered invalid/missing and excluded from computation.
  • strideMask: stride length for mask.

The N and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to compute the minimum value of every other element in x,

var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );

var x = new Float64Array( [ 1.0, 2.0, 7.0, -2.0, -4.0, 3.0, -5.0, -6.0 ] );
var mask = new Uint8Array( [ 0, 0, 0, 0, 0, 0, 1, 1 ] );

var v = dmskmin( 4, x, 2, mask, 2 );
// returns -4.0

Note that indexing is relative to the first index. To introduce offsets, use typed array views.

var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );

var x0 = new Float64Array( [ 2.0, 1.0, -2.0, -2.0, 3.0, 4.0, -5.0, -6.0 ] );
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var mask0 = new Uint8Array( [ 0, 0, 0, 0, 0, 0, 1, 1 ] );
var mask1 = new Uint8Array( mask0.buffer, mask0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var v = dmskmin( 4, x1, 2, mask1, 2 );
// returns -2.0

dmskmin.ndarray( N, x, strideX, offsetX, mask, strideMask, offsetMask )

Computes the minimum value of a double-precision floating-point strided array according to a mask and using alternative indexing semantics.

var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );

var x = new Float64Array( [ 1.0, -2.0, -4.0, 2.0 ] );
var mask = new Uint8Array( [ 0, 0, 1, 0 ] );

var v = dmskmin.ndarray( x.length, x, 1, 0, mask, 1, 0 );
// returns -2.0

The function has the following additional parameters:

  • offsetX: starting index for x.
  • offsetMask: starting index for mask.

While typed array views mandate a view offset based on the underlying buffer, the offset parameters support indexing semantics based on a starting indices. For example, to calculate the minimum value for every other element in x starting from the second element

var Float64Array = require( '@stdlib/array/float64' );
var Uint8Array = require( '@stdlib/array/uint8' );

var x = new Float64Array( [ 2.0, 1.0, -2.0, -2.0, 3.0, 4.0, -5.0, -6.0 ] );
var mask = new Uint8Array( [ 0, 0, 0, 0, 0, 0, 1, 1 ] );

var v = dmskmin.ndarray( 4, x, 2, 1, mask, 2, 1 );
// returns -2.0

Notes

  • If N <= 0, both functions return NaN.

Examples

var uniform = require( '@stdlib/random/array/uniform' );
var bernoulli = require( '@stdlib/random/array/bernoulli' );
var dmskmin = require( '@stdlib/stats/base/dmskmin' );

var uniformOptions = {
    'dtype': 'float64'
};
var bernoulliOptions = {
    'dtype': 'uint8'
};

var x = uniform( 10, -50.0, 50.0, uniformOptions );
var mask = bernoulli( x.length, 0.2, bernoulliOptions );
console.log( x );
console.log( mask );

var v = dmskmin( x.length, x, 1, mask, 1 );
console.log( v );

Usage

#include "stdlib/stats/base/dmskmin.h"

stdlib_strided_dmskmin( N, *X, strideX, *Mask, strideMask )

Computes the minimum value of a double-precision floating-point strided array according to a mask.

#include <stdint.h>

const double x[] = { 1.0, -2.0, 2.0 };
const uint8_t mask[] = { 0, 1, 0 };

double v = stdlib_strided_dmskmin( 3, x, 1, mask, 1 );
// returns 1.0

The function accepts the following arguments:

  • N: [in] CBLAS_INT number of indexed elements.
  • X: [in] double* input array.
  • strideX: [in] CBLAS_INT stride length for X.
  • Mask: [in] uint8_t* mask array. If a Mask array element is 0, the corresponding element in X is considered valid and included in computation. If a Mask array element is 1, the corresponding element in X is considered invalid/missing and excluded from computation.
  • strideMask: [in] CBLAS_INT stride length for Mask.
double stdlib_strided_dmskmin( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const uint8_t *Mask, const CBLAS_INT strideMask );

stdlib_strided_dmskmin_ndarray( N, *X, strideX, offsetX, *Mask, strideMask, offsetMask )

Computes the minimum value of a double-precision floating-point strided array according to a mask and using alternative indexing semantics.

#include <stdint.h>

const double x[] = { 1.0, -2.0, 2.0 };
const uint8_t mask[] = { 0, 1, 0 };

double v = stdlib_strided_dmskmin( 3, x, 1, 0, mask, 1, 0 );
// returns 1.0

The function accepts the following arguments:

  • N: [in] CBLAS_INT number of indexed elements.
  • X: [in] double* input array.
  • strideX: [in] CBLAS_INT stride length for X.
  • offsetX: [in] CBLAS_INT starting index for X.
  • Mask: [in] uint8_t* mask array. If a Mask array element is 0, the corresponding element in X is considered valid and included in computation. If a Mask array element is 1, the corresponding element in X is considered invalid/missing and excluded from computation.
  • strideMask: [in] CBLAS_INT stride length for Mask.
  • offsetMask: [in] CBLAS_INT starting index for Mask.
double stdlib_strided_dmskmin_ndarray( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX, const uint8_t *Mask, const CBLAS_INT strideMask, const CBLAS_INT offsetMask );

Examples

#include "stdlib/stats/base/dmskmin.h"
#include <stdint.h>
#include <stdio.h>

int main( void ) {
    // Create a strided array:
    const double x[] = { 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 };

    // Create a mask array:
    const uint8_t mask[] = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1 };

    // Specify the number of elements:
    const int N = 5;

    // Specify the stride lengths:
    const int strideX = 2;
    const int strideMask = 2;

    // Compute the minimum value:
    double v = stdlib_strided_dmskmin( N, x, strideX, mask, strideMask );

    // Print the result:
    printf( "min: %lf\n", v );
}

See Also

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