Python list (zipobject) returns empty (list) container
I got a weird problem in Python 3.4.3 and it is not mentioned anywhere.
Let's say: a = [1,2,3,4]
andb = [5,6,7,8]
To merge them vertically: ab = zip(a,b)
in python 3, ab
itself will return:
zip object in (some hexometer)
Everything is fine here in python 3 for a merged list: aabb = list(ab)
Now the problem, for the first time, aabb
will actually return a real list:[(1, 5), (2, 6), (3, 7), (4, 8)]
A second time and onward, however, if you do the whole process again list(aabb)
it will just return an empty container []
like it would list()
.
It will only work after a shell / interpreter restart.
Is this normal or a bug?
EDIT : Ok guys, I didn't understand what it was related to zip
, it is SEEMED constant since ab
it was returning the same hex value every time, so I thought it was related to list(ab)
.
In any case, worked out by reassigning ab = zip(ab)
From what I understand in the answers and the original link is ab
set after reading.
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This issue will not be generated list(aabb)
, but with list(ab)
in your code right now:
a = [1, 2, 3, 4] b = [5, 6, 7, 8] ab = zip(a, b) aabb = list(ab) print(list(ab))
The problem is that there zip
is a generator that stores the values once and then located like this:
a = [1, 2, 3, 4]
b = [5, 6, 7, 8]
ab = zip(a, b) # generator expression created by the zip function
aabb = list(ab) # element read from ab, disposed, placed in a list
print(list(ab)) # now ab has nothing because it was disposed
This, on the other hand, should work, because aabb
- it's just a list, not a disposed generator ab
:
a = [1, 2, 3, 4] b = [5, 6, 7, 8] ab = zip(a, b) aabb = list(ab) print(list(aabb))
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