ubique/lib/matarrs/reshape.js

A mathematical and quantitative library for Javascript and Node.js

/**
 * Sorting and Reshaping Arrays
 */
 module.exports = function($u) {
 /**
 * @method  reshape
 * @summary Reshape array or matrix with custom values
 * @description  Reshape array or matrix with custom values based on rows values of X
 *
 * @param  {array|matrix} x array or matrix of elements
 * @param  {number} m number of rows for the new matrix
 * @param  {number} n number of cols for the new matrix
 * @param  {number} flag flag 0: rowwise element, 1: columnwise (def: 0)
 * @return {matrix}     
 *
 * @example 
 * ubique.reshape([5,6,3],3,1);
 * // [ [ 5 ], [ 6 ], [ 3 ] ]
 *
 * ubique.reshape([5,6,3],1,3);
 * // [ 5, 6, 3 ]
 * 
 * ubique.reshape([[-1,3,-1],[4,5,9]],3,2);
 * // [ [ -1, 4 ], [ 3, 5 ], [ -1, 9 ] ]
 *
 * ubique.reshape([[-1,3,-1],[4,5,9]],3,2,1);
 * // [ [ -1, 5 ], [ 4, -1 ], [ 3, 9 ] ]
 * 
 * ubique.reshape([[-1,3,-1],[4,5,9]],6,1);
 * // [ [ -1 ], [ 3 ], [ -1 ], [ 4 ], [ 5 ], [ 9 ] ]
 *
 * ubique.reshape([[-1,3,-1],[4,5,9]],6,1,1);
 * // [ [ -1 ], [ 4 ], [ 3 ], [ 5 ], [ -1 ], [ 9 ] ]
 */
 $u.reshape = function(x,m,n,flag) {
 	if (arguments.length < 3) {
 		throw new Error('not enough input arguments');
 	}
  flag = flag == null ? 0 : flag;
 	if (!$u.isinteger(m) || !$u.isinteger(n)) {
 		throw new Error('dimensions must be integer numbers');
 	}
 	var nrows = $u.nrows(x);
 	var ncols = $u.ncols(x);
 	var totsiz = nrows * ncols;
 	if ((m * n) !== totsiz ) {
 		throw new Error('total number of elements must be the same');
 	}
 	if ($u.isnumber(x)) {
 		return x;
 	} else 
 	if ($u.isarray(x)) {
 		if (m === nrows && n === ncols) {
 			return x;
 		} else {
 			return $u.transpose(x);
 		}
 	} else 
 	if ($u.ismatrix(x)) {
 		var out = $u.matrix(m,n,NaN);
 		var vec = $u.flatten(x,flag); // flatten by rows
 		for (var i = 0;i < m * n;i++) {
 			var idx = $u.ind2sub([m,n],i);
 			out[idx[0]][idx[1]] = vec[i];
 		}
 		return out;
 	} else {
 		throw new Error('unknown input arguments');
 	}

 }
}