algorithm - creating a spiral array in python? -

me , mate trying create fun game in python elements entered in array accessed in spiral manner. have tried few methods 1 given below (source).

def spiral(x, y):   x = y = 0   dx = 0   dy = -1   in range(max(x, y)**2):     if (-x/2 < x <= x/2) , (-y/2 < y <= y/2):         print (x, y)         # stuff...     if x == y or (x < 0 , x == -y) or (x > 0 , x == 1-y):         dx, dy = -dy, dx     x, y = x+dx, y+dy 

the above statement accesses elements in spiral loop , prints them defined array ae. know how can transform given array ae spiral 1

you can build spiral starting near center of matrix , turning right unless element has been visited already:

#!/usr/bin/env python north, s, w, e = (0, -1), (0, 1), (-1, 0), (1, 0) # directions turn_right = {north: e, e: s, s: w, w: north} # old -> new direction  def spiral(width, height):     if width < 1 or height < 1:         raise valueerror     x, y = width // 2, height // 2 # start near center     dx, dy = north # initial direction     matrix = [[none] * width _ in range(height)]     count = 0     while true:         count += 1         matrix[y][x] = count # visit         # try turn right         new_dx, new_dy = turn_right[dx,dy]         new_x, new_y = x + new_dx, y + new_dy         if (0 <= new_x < width , 0 <= new_y < height ,             matrix[new_y][new_x] none): # can turn right             x, y = new_x, new_y             dx, dy = new_dx, new_dy         else: # try move straight             x, y = x + dx, y + dy             if not (0 <= x < width , 0 <= y < height):                 return matrix # go  def print_matrix(matrix):     width = len(str(max(el row in matrix el in row if el not none)))     fmt = "{:0%dd}" % width     row in matrix:         print(" ".join("_"*width if el none else fmt.format(el) el in row)) 

example:

>>> print_matrix(spiral(5, 5)) 21 22 23 24 25 20 07 08 09 10 19 06 01 02 11 18 05 04 03 12 17 16 15 14 13