refactor: duplicate shape iteration and fix annotation

lib/node_modules/@stdlib/ndarray/base/map/lib/index.js

@@ -48,7 +48,6 @@
 *
 * // Create the input and output ndarray-like objects:
 * var x = {
-* 'ref': null,
 * 'dtype': 'float64',
 * 'data': xbuf,
 * 'shape': shape,

lib/node_modules/@stdlib/ndarray/base/map/lib/main.js

@@ -23,7 +23,6 @@
 var iterationOrder = require( '@stdlib/ndarray/base/iteration-order' );
 var minmaxViewBufferIndex = require( '@stdlib/ndarray/base/minmax-view-buffer-index' );
 var ndarray2object = require( '@stdlib/ndarray/base/ndarraylike2object' );
-var numel = require( '@stdlib/ndarray/base/numel' );
 var blockedaccessormap2d = require( './2d_blocked_accessors.js' );
 var blockedaccessormap3d = require( './3d_blocked_accessors.js' );
 var blockedmap2d = require( './2d_blocked.js' );
@@ -81,7 +80,6 @@ var MAX_DIMS = MAP.length -1;
 * - **offset**: index offset.
 * - **order**: specifies whether an ndarray is row-major (C-style) or column major (Fortran-style).
 *
-* @private
 * @param {ArrayLikeObject<Object>} arrays - array-like object containing one input array and one output array
 * @param {Callback} fcn - callback function
 * @param {*} [thisArg] - callback execution context
@@ -113,7 +111,6 @@ var MAX_DIMS = MAP.length -1;
 *
 * // Create the input and output ndarray-like objects:
 * var x = {
-* 'ref': null,
 * 'dtype': 'float64',
 * 'data': xbuf,
 * 'shape': shape,
@@ -163,7 +160,6 @@ function map( arrays, fcn, thisArg ) {
  shx = x.shape;
  shy = y.shape;
  ndims = shx.length;
- len = numel( shx );
  if ( ndims !== shy.length ) {
  throw new Error( 'invalid arguments. Arrays must have the same number of dimensions (i.e., same rank). ndims(x) == '+ndims+'. ndims(y) == '+shy.length+'.' );
  }
@@ -174,22 +170,26 @@ function map( arrays, fcn, thisArg ) {
  }
  return MAP[ ndims ]( x, y, fcn, thisArg );
  }
- // Check whether we were provided an empty ndarray...
- if ( len === 0 ) {
- return;
- }
  // Verify that the input and output arrays have the same dimensions...
+ len = 1; // number of elements
  ns = 0; // number of singleton dimensions
  for ( i = 0; i < ndims; i++ ) {
  d = shx[ i ];
  if ( d !== shy[ i ] ) {
  throw new Error( 'invalid arguments. Array must have the same shape.' );
  }
+ // Note that, if one of the dimensions is `0`, the length will be `0`...
+ len *= d;
+
  // Check whether the current dimension is a singleton dimension...
  if ( d === 1 ) {
  ns += 1;
  }
  }
+ // Check whether we were provided empty ndarrays...
+ if ( len === 0 ) {
+ return;
+ }
  // Determine whether the ndarrays are one-dimensional and thus readily translate to one-dimensional strided arrays...
  if ( ndims === 1 ) {
  if ( x.accessorProtocol || y.accessorProtocol ) {