Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 | 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 20x 20x 20x 56x 56x 56x 20x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 1058x 1058x 1058x 1058x 1058x 1058x 1058x 1058x 1058x 1058x 1058x 1058x 1058x 1672x 1672x 1672x 804x 804x 1672x 868x 868x 1672x 1058x 1058x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 95x 402x 402x 402x 402x 95x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 214x 214x 214x 4x 4x 214x 20x 20x 20x 20x 214x 95x 95x 95x 95x 95x 214x 3x 3x 3x 3x 3x | /**
* @license Apache-2.0
*
* Copyright (c) 2023 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* eslint-disable max-len */
'use strict';
// MODULES //
var shape2strides = require( '@stdlib/ndarray/base/shape2strides' );
var vind2bind = require( '@stdlib/ndarray/base/vind2bind' );
var numel = require( '@stdlib/ndarray/base/numel' );
var grev = require( '@stdlib/blas/ext/base/grev' );
var zeros = require( '@stdlib/array/base/zeros' );
var copy = require( '@stdlib/array/base/copy-indexed' );
// VARIABLES //
var MODE = 'throw';
// FUNCTIONS //
/**
* Copies a specified number of array elements to a provided array according to a callback function.
*
* @private
* @param {Array} x - input array
* @param {NonNegativeInteger} N - number of elements to copy
* @param {Collection} out - output array
* @param {integer} stride - output array stride
* @param {NonNegativeInteger} offset - output array offset
* @param {Function} clbk - callback function
* @param {*} [thisArg] - callback execution context
*
* @example
* function scale( v ) {
* return v * 2;
* }
*
* var x = [ 1, 2, 3, 4 ];
*
* var out = [ 0, 0, 0 ];
* copyBy( x, 3, out, 1, 0, scale );
*
* var o = out;
* // returns [ 2, 4, 6 ]
*/
function copyBy( x, N, out, stride, offset, clbk, thisArg ) {
var i;
for ( i = 0; i < N; i++ ) {
out[ offset ] = clbk.call( thisArg, x[ i ], [ i ], x );
offset += stride;
}
}
/**
* Recursively flattens an array in lexicographic order.
*
* @private
* @param {Array} orig - original input array
* @param {Array} x - array to flatten
* @param {NonNegativeInteger} ndims - number of dimensions in the input array
* @param {NonNegativeIntegerArray} shape - shape of the input array
* @param {NonNegativeInteger} dim - dimension index
* @param {NonNegativeIntegerArray} indices - outer array element indices
* @param {Collection} out - output array
* @param {integer} stride - output array stride
* @param {NonNegativeInteger} offset - output array offset
* @param {Function} clbk - callback function
* @param {*} [thisArg] - callback execution context
* @returns {NonNegativeInteger} offset for next output array element
*/
function recurseLexicographic( orig, x, ndims, shape, dim, indices, out, stride, offset, clbk, thisArg ) { // eslint-disable-line max-params
var FLG;
var idx;
var S;
var d;
var i;
// Check whether we've reached the last dimension:
d = dim + 1;
FLG = ( d === ndims );
S = shape[ dim ];
for ( i = 0; i < S; i++ ) {
idx = indices.slice(); // we explicitly copy in order to avoid potential mutation when calling `clbk`
idx.push( i );
if ( FLG ) {
out[ offset ] = clbk.call( thisArg, x[ i ], idx, orig );
offset += stride;
} else {
offset = recurseLexicographic( orig, x[ i ], ndims, shape, d, idx, out, stride, offset, clbk, thisArg );
}
}
return offset;
}
/**
* Flattens an array in colexicographic order.
*
* @private
* @param {Array} x - array to flatten
* @param {NonNegativeInteger} ndims - number of dimensions in the input array
* @param {NonNegativeIntegerArray} shape - shape of the input array
* @param {Collection} out - output array
* @param {integer} stride - output array stride
* @param {NonNegativeInteger} offset - output array offset
* @param {Function} clbk - callback function
* @param {*} [thisArg] - callback execution context
*/
function flattenColexicographic( x, ndims, shape, out, stride, offset, clbk, thisArg ) {
var len;
var tmp;
var ord;
var sh;
var sx;
var j;
var i;
// Note that, in contrast to lexicographic iteration, we cannot readily define a straightforward recursive definition for colexicographic iteration. Accordingly, we have to perform a workaround in which we first flatten in lexicographic order and then perform an out-of-place transposition to return an array in colexicographic order.
// Determine how many elements will be in the output array:
len = numel( shape );
// For input arrays having an arbitrary number of dimensions, first flatten in lexicographic order:
tmp = zeros( len );
recurseLexicographic( x, x, ndims, shape, 0, [], tmp, 1, 0, clbk, thisArg );
// Define the memory layout:
ord = 'row-major';
// Generate a stride array for lexicographic order:
sx = shape2strides( shape, ord );
// Reverse the dimensions and strides (i.e., define the shape and strides of the transpose):
sh = copy( shape );
grev( ndims, sh, 1 );
grev( ndims, sx, 1 );
// Iterate over each element based on the linear **view** index (note: this has negative performance implications due to lack of data locality)...
for ( i = 0; i < len; i++ ) {
j = vind2bind( sh, sx, 0, ord, i, MODE );
out[ offset ] = tmp[ j ];
offset += stride;
}
}
// MAIN //
/**
* Flattens an n-dimensional nested array according to a callback function and assigns elements to a provided output array.
*
* ## Notes
*
* - The function assumes that all nested arrays have the same length (i.e., the input array is **not** a ragged array).
*
* @param {Array} x - input nested array
* @param {NonNegativeIntegerArray} shape - array shape
* @param {boolean} colexicographic - specifies whether to flatten array values in colexicographic order
* @param {Collection} out - output array
* @param {integer} stride - output array stride
* @param {NonNegativeInteger} offset - output array index offset
* @param {Function} clbk - callback function
* @param {*} [thisArg] - callback execution context
* @returns {Collection} output array
*
* @example
* var Float64Array = require( '@stdlib/array/float64' );
*
* function scale( v ) {
* return v * 2;
* }
*
* var x = [ [ 1, 2 ], [ 3, 4 ] ];
*
* var out = flattenBy( x, [ 2, 2 ], false, new Float64Array( 4 ), 1, 0, scale );
* // returns <Float64Array>[ 2, 4, 6, 8 ]
*
* @example
* var Float64Array = require( '@stdlib/array/float64' );
*
* function scale( v ) {
* return v * 2;
* }
*
* var x = [ [ 1, 2 ], [ 3, 4 ] ];
*
* var out = flattenBy( x, [ 2, 2 ], true, new Float64Array( 4 ), 1, 0, scale );
* // returns <Float64Array>[ 2, 6, 4, 8 ]
*/
function flattenBy( x, shape, colexicographic, out, stride, offset, clbk, thisArg ) {
var ndims = shape.length;
if ( ndims === 0 ) { // 0-dimensional array
return out;
}
if ( ndims === 1 ) { // 1-dimensional array
// For 1-dimensional arrays, we can perform simple iteration:
copyBy( x, shape[ 0 ], out, stride, offset, clbk, thisArg );
return out;
}
if ( colexicographic ) {
flattenColexicographic( x, ndims, shape, out, stride, offset, clbk, thisArg );
return out;
}
recurseLexicographic( x, x, ndims, shape, 0, [], out, stride, offset, clbk, thisArg );
return out;
}
// EXPORTS //
module.exports = flattenBy;
|