替代在Python中嵌套循环 [英] Alternative to nesting for loops in Python

问题描述

我已经读过，Python的一个关键信念就是flat> nested。但是，如果我有几个变量计数，什么是多个循环的替代？
我的代码是用于计算网格总和，如下所示：

  def horizo​​ntal（）：
 for x在范围内（20）：
在范围内（17）：
 temp = grid [x] [y：y + 4] 
 sum = 0 
 for n in temp：
 sum + = int（n）
 print sum＃编辑：返回而不是打印错误
  

这在我看来好像太嵌套了。首先，Python中的许多嵌套循环被认为是什么（我之前肯定见过2个嵌套循环）。其次，如果嵌套太重，那么编写这个代码的另一种方法是什么？

解决方案

  b 
 
 
 
 $ b $（$）
 
 $ （int（n）for grid [x] [y：y + 4]）
  

应该使用 sum 函数。当然，如果你用一个变量来映射它，所以我改变它为 my_sum

I've read that one of the key beliefs of Python is that flat > nested. However, if I have several variables counting up, what is the alternative to multiple for loops? My code is for counting grid sums and goes as follows:

def horizontal():
    for x in range(20):
        for y in range(17):
            temp = grid[x][y: y + 4]
            sum = 0
            for n in temp:
                sum += int(n)
            print sum # EDIT: the return instead of print was a mistype

This seems to me like it is too heavily nested. Firstly, what is considered to many nested loops in Python ( I have certainly seen 2 nested loops before). Secondly, if this is too heavily nested, what is an alternative way to write this code?

解决方案

from itertools import product

def horizontal():
    for x, y in product(range(20), range(17)):
        print 1 + sum(int(n) for n in grid[x][y: y + 4])

You should be using the sum function. Of course you can't if you shadow it with a variable, so I changed it to my_sum

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