139 lines
3.3 KiB
JavaScript
139 lines
3.3 KiB
JavaScript
/**
|
|
* @license Apache-2.0
|
|
*
|
|
* Copyright (c) 2018 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.
|
|
*/
|
|
|
|
'use strict';
|
|
|
|
// MODULES //
|
|
|
|
var isArray = require( '@stdlib/assert/is-array' );
|
|
|
|
|
|
// FUNCTIONS //
|
|
|
|
/**
|
|
* Recursively (and eagerly) attempts to resolve nested array dimensions.
|
|
*
|
|
* @private
|
|
* @param {Array} shape - output array
|
|
* @param {Array} arr - array
|
|
* @returns {Array} shape array
|
|
*/
|
|
function recurse( shape, arr ) {
|
|
var v = arr[ 0 ];
|
|
if ( isArray( v ) ) {
|
|
shape.push( v.length );
|
|
recurse( shape, v );
|
|
}
|
|
return shape;
|
|
}
|
|
|
|
/**
|
|
* Recursively verifies that all nested arrays have consistent dimensions.
|
|
*
|
|
* @private
|
|
* @param {PositiveInteger} ndims - number of dimensions
|
|
* @param {Array} shape - shape array
|
|
* @param {NonNegativeInteger} d - dimension
|
|
* @param {Array} arr - array element to verify
|
|
* @param {boolean} flg - boolean indicating whether to continue recursing
|
|
* @returns {NonNegativeInteger} number of consistent dimensions
|
|
*/
|
|
function check( ndims, shape, d, arr, flg ) {
|
|
var len;
|
|
var v;
|
|
var i;
|
|
|
|
// Get the size of the current dimension:
|
|
len = shape[ d ];
|
|
|
|
// Ensure that each array element is an array of the same size:
|
|
for ( i = 0; i < arr.length; i++ ) {
|
|
v = arr[ i ];
|
|
|
|
// If the array element is not an array or is not the same size, we have found an inconsistent dimension:
|
|
if ( !isArray( v ) || v.length !== len ) {
|
|
// `d` is one more than the index of the last consistent dimension and thus equal to the number of consistent dimensions:
|
|
return d;
|
|
}
|
|
// Recursively examine nested elements:
|
|
if ( flg ) {
|
|
v = check( ndims, shape, d+1, v, d+1 < ndims-1 );
|
|
if ( v < ndims ) {
|
|
// Propagate the number of consistent dimensions up the recursion chain...
|
|
return v;
|
|
}
|
|
}
|
|
}
|
|
return ndims;
|
|
}
|
|
|
|
|
|
// MAIN //
|
|
|
|
/**
|
|
* Determines (nested) array dimensions.
|
|
*
|
|
* @param {Array} arr - array
|
|
* @throws {TypeError} must provide an array
|
|
* @returns {Array} array shape
|
|
*
|
|
* @example
|
|
* var arr = [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ];
|
|
*
|
|
* var shape = arrayShape( arr );
|
|
* // returns [ 3, 3 ]
|
|
*
|
|
* @example
|
|
* var arr = [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8 ] ];
|
|
*
|
|
* var shape = arrayShape( arr );
|
|
* // returns [ 3 ]
|
|
*
|
|
* @example
|
|
* var arr = [ [ 1, 2, 3 ], [ 4, 5, 6 ], null ];
|
|
*
|
|
* var shape = arrayShape( arr );
|
|
* // returns [ 3 ]
|
|
*/
|
|
function arrayShape( arr ) {
|
|
var shape;
|
|
var ndims;
|
|
|
|
if ( !isArray( arr ) ) {
|
|
throw new TypeError( 'invalid argument. Must provide an array. Value: `' + arr + '`.' );
|
|
}
|
|
// Initialize the shape/dimensions array:
|
|
shape = [ arr.length ];
|
|
|
|
// Eagerly determine array dimensions:
|
|
recurse( shape, arr );
|
|
ndims = shape.length;
|
|
|
|
// Check that all array element dimensions are consistent:
|
|
if ( ndims > 1 ) {
|
|
// If `check()` returns a value less than `ndims`, trim off the inconsistent dimensions:
|
|
shape.length = check( ndims, shape, 1, arr, ndims > 2 );
|
|
}
|
|
return shape;
|
|
}
|
|
|
|
|
|
// EXPORTS //
|
|
|
|
module.exports = arrayShape;
|