pp = [[11,22,33],[111,44,55],[77,88,99]]

将二维列表转为一维列表

1、方法一 列表推导式

ii = [i for p in pp for i in p]
print("ii={}".format(ii))    # ii=[11, 22, 33, 111, 44, 55, 77, 88, 99]

2、方法二flatten，此方法结果输出列表中为空格间隔，且二维列表中必须是相等数量的元素

import numpy as np
n = np.array(pp).flatten()
print("n={}".format(n))    # [ 11  22  33 111  44  55  77  88  99]

3、方法三 sum()

s = sum(pp,[])
print("s={}".format(s))    #s=[11, 22, 33, 111, 44, 55, 77, 88, 99]

4、方法四operator

import operator
from functools import reduce
rr = (reduce(operator.add,pp))
print("rr={}".format(rr))    # rr=[11, 22, 33, 111, 44, 55, 77, 88, 99]

5、方法五itertools

from itertools import chain
it = list(chain.from_iterable(pp))
print("it={}".format(it))    # it=[11, 22, 33, 111, 44, 55, 77, 88, 99]