面试真题之Python二维数组转为一维数组的四种方法

arr = [
	[1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]

1. 列表推导式

   rst = [x for i in arr for x in i]
   

2. sum

   rst = sum(arr, [])
   

3. itertools

   from itertools import chain
   
   rst = list(chain.from_iterable(arr))
   

4. operator

   import operator
   from functools import reduce
   
   rst = reduce(operator.add, arr)