自己用python写的螺旋矩阵生成算法

如果输入6，可以生成如下矩阵：
1  20 19 18 17 16
2  21 32 31 30 15
3  22 33 36 29 14
4  23 34 35 28 13
5  24 25 26 27 12
6  7  8  9  10 11
代码如下：

import string
import sys
def outputcirclenumber(m):
        x=0
        y=0
        edgelayer = 0
        change_direction_count = 0
        clockwise =1
        direction =1 #1,2,3,4
        outputNum =1
        odd = m%2
        a = []
        for j in range(0,m):
                b = [0 for i in range(0,m)]
                a.append(b)
        #check if the current point is in the corner now,if it is ,change the direction
        def checkatcorner(x,y,m,edgelayer,direction):
                if x+y<1:
                        return 0
                if x==edgelayer and y==edgelayer+1 and direction==4:
                        return 1
                if x==m-1-edgelayer and y==edgelayer:
                        return 2
                if x==m-1-edgelayer and y==m-1-edgelayer:
                        return 3
                if x==edgelayer and y==m-1-edgelayer :
                        return 4
                return 0

        while True:
                if checkatcorner(x,y,m,edgelayer,direction):
                        direction = checkatcorner(x,y,m,edgelayer,direction)
                        change_direction_count = change_direction_count +1
                        if not change_direction_count%4 and change_direction_count >0:
                             edgelayer = edgelayer+1
                if x==0 and y==0:
                        a[x][y] = outputNum
                        outputNum = outputNum +1
                if direction ==1:
                        x = x+1
                        a[x][y] = outputNum
                if direction ==2:
                        y = y+1
                        a[x][y] = outputNum
                if direction ==3:
                        x = x-1;
                        a[x][y] = outputNum
                if direction ==4:
                        y = y-1;
                        a[x][y] = outputNum
                outputNum = outputNum +1        
                if odd and x == y and x==m/2 and y==m/2:
                        break
                if not odd and x==m/2-1 and y==m/2:
                        break
        return a

#below is the main functions
if __name__ != "__main__":
        print    "outside call error"
        sys.exit()

number    = raw_input("please input the number you want to generate circle matrix:")

try:
        num = int(number)
except:
        print "\n\nNumber type error\n\n"
if num<=1:
        print    "number must greater than 1!!!"
        sys.exit()
        
result = outputcirclenumber(num)
for i in result:
        for j in i:
                print string.rjust(str(j),len(str(num*num)),' '),
        print