额风火编程--内置生成器函数groupby()和zip() / longest(),分组和打包, max() / min()聚合函数

groupby(seq, key)

对seq中连续的元素按照key的返回值进行分组, 不连续的重新分组.
DEMO
from itertools import groupby
s = “1221”
gen = groupby(s)
for var, group in gen:
print(var, list(group))

zip_longest(seq1, seq2, fillvalue=None)

按照最长序列组包, fillvalue指定填充值.
DEMO
from itertools import zip_longest
s1 = “111”
s2 = “22222”
r = zip_longest(s1,s2, fillvalue=“x”)
print(list®)

max/min(seq, key=None, default)
比较seq各元素输入key的返回结果, 如果seq为空返回default.
DEMO

li = [“1”,“22”,“3”]
r = max(li,key=len, default=“0”)
print®