154 lines
4.2 KiB
JavaScript
154 lines
4.2 KiB
JavaScript
/**
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* @license Apache-2.0
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*
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* Copyright (c) 2021 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MAIN //
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/**
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* Applies a unary callback to elements in a two-dimensional input ndarray and assigns results to elements in an equivalently shaped output ndarray.
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*
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* @private
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* @param {Object} x - object containing input ndarray meta data
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* @param {string} x.dtype - data type
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* @param {Collection} x.data - data buffer
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* @param {NonNegativeIntegerArray} x.shape - dimensions
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* @param {IntegerArray} x.strides - stride lengths
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* @param {NonNegativeInteger} x.offset - index offset
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* @param {string} x.order - specifies whether `x` is row-major (C-style) or column-major (Fortran-style)
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* @param {Object} y - object containing output ndarray meta data
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* @param {string} y.dtype - data type
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* @param {Collection} y.data - data buffer
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* @param {NonNegativeIntegerArray} y.shape - dimensions
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* @param {IntegerArray} y.strides - stride lengths
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* @param {NonNegativeInteger} y.offset - index offset
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* @param {string} y.order - specifies whether `y` is row-major (C-style) or column-major (Fortran-style)
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* @param {Callback} fcn - unary callback
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* @returns {void}
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*
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* @example
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* var Float64Array = require( '@stdlib/array/float64' );
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*
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* function scale( x ) {
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* return x * 10.0;
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* }
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*
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* // Create data buffers:
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* var xbuf = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 ] );
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* var ybuf = new Float64Array( 4 );
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*
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* // Define the shape of the input and output arrays:
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* var shape = [ 2, 2 ];
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*
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* // Define the array strides:
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* var sx = [ 4, 1 ];
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* var sy = [ 2, 1 ];
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*
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* // Define the index offsets:
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* var ox = 1;
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* var oy = 0;
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*
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* // Create the input and output ndarray-like objects:
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* var x = {
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* 'dtype': 'float64',
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* 'data': xbuf,
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* 'shape': shape,
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* 'strides': sx,
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* 'offset': ox,
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* 'order': 'row-major'
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* };
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* var y = {
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* 'dtype': 'float64',
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* 'data': ybuf,
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* 'shape': shape,
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* 'strides': sy,
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* 'offset': oy,
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* 'order': 'row-major'
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* };
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*
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* // Apply the unary function:
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* unary2d( x, y, scale );
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*
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* console.log( y.data );
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* // => <Float64Array>[ 20.0, 30.0, 60.0, 70.0 ]
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*/
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function unary2d( x, y, fcn ) {
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var xbuf;
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var ybuf;
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var dx0;
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var dx1;
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var dy0;
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var dy1;
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var sh;
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var S0;
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var S1;
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var sx;
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var sy;
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var ix;
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var iy;
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var i0;
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var i1;
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// Note on variable naming convention: S#, dx#, dy#, i# where # corresponds to the loop number, with `0` being the innermost loop...
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// Extract loop variables for purposes of loop interchange: dimensions and loop offset (pointer) increments...
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sh = x.shape;
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sx = x.strides;
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sy = y.strides;
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if ( x.order === 'row-major' ) {
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// For row-major ndarrays, the last dimensions have the fastest changing indices...
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S0 = sh[ 1 ];
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S1 = sh[ 0 ];
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dx0 = sx[ 1 ]; // offset increment for innermost loop
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dx1 = sx[ 0 ] - ( S0*sx[1] ); // offset increment for outermost loop
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dy0 = sy[ 1 ];
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dy1 = sy[ 0 ] - ( S0*sy[1] );
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} else { // order === 'column-major'
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// For column-major ndarrays, the first dimensions have the fastest changing indices...
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S0 = sh[ 0 ];
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S1 = sh[ 1 ];
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dx0 = sx[ 0 ]; // offset increment for innermost loop
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dx1 = sx[ 1 ] - ( S0*sx[0] ); // offset increment for outermost loop
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dy0 = sy[ 0 ];
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dy1 = sy[ 1 ] - ( S0*sy[0] );
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}
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// Set the pointers to the first indexed elements in the respective ndarrays...
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ix = x.offset;
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iy = y.offset;
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// Cache references to the input and output ndarray buffers...
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xbuf = x.data;
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ybuf = y.data;
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// Iterate over the ndarray dimensions...
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for ( i1 = 0; i1 < S1; i1++ ) {
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for ( i0 = 0; i0 < S0; i0++ ) {
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ybuf[ iy ] = fcn( xbuf[ ix ] );
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ix += dx0;
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iy += dy0;
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}
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ix += dx1;
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iy += dy1;
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}
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}
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// EXPORTS //
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module.exports = unary2d;
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