minViewBufferIndex
Compute the minimum linear index in an underlying data buffer accessible to an array view.
Usage
var minViewBufferIndex = require( '@stdlib/ndarray/base/min-view-buffer-index' );
minViewBufferIndex( shape, strides, offset )
Computes the minimum linear index in an underlying data buffer accessible to an array view.
// Array shape:
var shape = [ 2, 2 ];
// Stride array:
var strides = [ -2, -1 ];
// Index offset which specifies the location of the first indexed value:
var offset = 13; // includes a view offset
var idx = minViewBufferIndex( shape, strides, offset );
// returns 10
Examples
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
var shape2strides = require( '@stdlib/ndarray/base/shape2strides' );
var strides2offset = require( '@stdlib/ndarray/base/strides2offset' );
var randu = require( '@stdlib/random/base/randu' );
var minViewBufferIndex = require( '@stdlib/ndarray/base/min-view-buffer-index' );
var strides;
var offset;
var shape;
var idx;
var i;
var j;
shape = [ 0, 0, 0 ];
for ( i = 0; i < 100; i++ ) {
// Generate a random array shape:
shape[ 0 ] = discreteUniform( 1, 10 );
shape[ 1 ] = discreteUniform( 1, 10 );
shape[ 2 ] = discreteUniform( 1, 10 );
// Generate strides:
if ( randu() < 0.5 ) {
strides = shape2strides( shape, 'row-major' );
} else {
strides = shape2strides( shape, 'column-major' );
}
j = discreteUniform( 0, shape.length-1 );
strides[ j ] *= ( randu() < 0.5 ) ? -1 : 1;
// Compute the index offset:
offset = strides2offset( shape, strides ) + 25; // include view offset
// Compute the minimum linear index:
idx = minViewBufferIndex( shape, strides, offset );
console.log( 'Shape: %s. Strides: %s. Offset: %d. Min idx: %d.', shape.join( 'x' ), strides.join( ',' ), offset, idx );
}
C APIs
Usage
#include "stdlib/ndarray/base/min_view_buffer_index.h"
stdlib_ndarray_min_view_buffer_index( ndims, *shape, *strides, offset )
Computes the minimum linear index (in bytes) in an underlying data buffer accessible to an array view.
#include <stdint.h>
int64_t ndims = 2;
int64_t shape[] = { 10, 10 };
int64_t strides[] = { 10, 1 };
int64_t offset = 10;
int64_t idx = stdlib_ndarray_min_view_buffer_index( ndims, shape, strides, offset );
// returns 10
The function accepts the following arguments:
- ndims:
[in] int64_t
number of dimensions. - shape:
[in] int64_t*
array shape (dimensions). - strides:
[in] int64_t*
array strides (in bytes). - offset:
[in] int64_t
index offset.
int64_t stdlib_ndarray_min_view_buffer_index( const int64_t ndims, const int64_t *shape, const int64_t *strides, const int64_t offset );
Examples
#include "stdlib/ndarray/base/min_view_buffer_index.h"
#include <stdint.h>
#include <stdio.h>
#include <inttypes.h>
int main( void ) {
// Specify the number of dimensions:
const int64_t ndims = 2;
// Define an array shape:
const int64_t shape[] = { 10, 10 };
// Define array strides:
const int64_t strides[] = { -2, 5 };
// Define an offset:
const int64_t offset = 100;
// Compute the minimum accessible index:
int64_t idx = stdlib_ndarray_min_view_buffer_index( ndims, shape, strides, offset );
// Print the results:
printf( "idx: %"PRId64"\n", idx );
}