Simply put, numpy.newaxis is used to increase the dimension of the existing array by one more dimension, when used once. Thus, 1D array will become 2D array 2D array will become 3D array 3D array will become 4D array 4D array will become 5D array and so on.. Here is a visual illustration which depicts … Read more
numpy.array is just a convenience function to create an ndarray; it is not a class itself. You can also create an array using numpy.ndarray, but it is not the recommended way. From the docstring of numpy.ndarray: Arrays should be constructed using array, zeros or empty … The parameters given here refer to a low-level method … Read more
O(n^2) time and O(1) space algorithm ( without any workarounds and hanky-panky stuff! ) Rotate by +90: Transpose Reverse each row Rotate by -90: Method 1 : Transpose Reverse each column Method 2 : Reverse each row Transpose Rotate by +180: Method 1: Rotate by +90 twice Method 2: Reverse each row and then reverse … Read more
As of PHP 5.3 the shortest solution seems to be array_walk_recursive() with the new closures syntax: function flatten(array $array) { $return = array(); array_walk_recursive($array, function($a) use (&$return) { $return[] = $a; }); return $return; }
Don’t use [[v]*n]*n, it is a trap! >>> a = [[0]*3]*3 >>> a [[0, 0, 0], [0, 0, 0], [0, 0, 0]] >>> a[0][0]=1 >>> a [[1, 0, 0], [1, 0, 0], [1, 0, 0]] but t = [ [0]*3 for i in range(3)] works great.
1. The meaning of shapes in NumPy You write, “I know literally it’s list of numbers and list of lists where all list contains only a number” but that’s a bit of an unhelpful way to think about it. The best way to think about NumPy arrays is that they consist of two parts, a … Read more
The current API is that: flatten always returns a copy. ravel returns a view of the original array whenever possible. This isn’t visible in the printed output, but if you modify the array returned by ravel, it may modify the entries in the original array. If you modify the entries in an array returned from … Read more
function searchForId($id, $array) { foreach ($array as $key => $val) { if ($val[‘uid’] === $id) { return $key; } } return null; } This will work. You should call it like this: $id = searchForId(‘100’, $userdb); It is important to know that if you are using === operator compared types have to be exactly same, … Read more
The purpose of meshgrid is to create a rectangular grid out of an array of x values and an array of y values. So, for example, if we want to create a grid where we have a point at each integer value between 0 and 4 in both the x and y directions. To create … Read more
Try the following: int[][] multi = new int[5][10]; … which is a short hand for something like this: int[][] multi = new int[5][]; multi[0] = new int[10]; multi[1] = new int[10]; multi[2] = new int[10]; multi[3] = new int[10]; multi[4] = new int[10]; Note that every element will be initialized to the default value for … Read more