map zip filter的区别

>>> res = map(lambda x:x**2,[1,2,3])
>>> type(res)
<class 'map'>
>>> res
<map object at 0x0000000003C1BF60>
>>> print(res)
<map object at 0x0000000003C1BF60>
>>> list(res)
[1, 4, 9]
>>> print(i for i in res)
<generator object <genexpr> at 0x0000000003D59840>
>>> res = map(lambda x,y : x+y, [1,2,3], [4,5,6])
>>> print([item for item in res])
[5, 7, 9]
>>> res = map(lambda x:x**2,[1,2,3])
>>> print([i for i in res])
[1, 4, 9]
>>> res = zip([1,2,3],[4,5,6])
>>> print([item for item in res])
[(1, 4), (2, 5), (3, 6)]
>>> res = filter(lambda x : x%2==0, [1,2,3,4,5,6])
>>> print([item for item in res])
[2, 4, 6]
>>> gen = (item for item in range(3))
>>> gen
<generator object <genexpr> at 0x0000000003D59840>
>>> gen.__next__()
0
>>> next(gen)
1
>>> next(gen)
2
>>> next(gen)
Traceback (most recent call last):
  File "<pyshell#21>", line 1, in <module>
    next(gen)
StopIteration
>>>