Tuple of lists concatenation - function vs comprehension
Ivan Evstegneev
webmailgroups at gmail.com
Sun Dec 7 10:07:31 EST 2014
Hello,
When I have worked in Python shell (IDLE) I found this issue:
>>>x = ([1, 2], [3, 4], [5, 6])
>>>L = []
>>>for I in x:
L.extend(i)
>>>L
[1,2,3,4,5,6]
But when I try to make comprehension using above expression, I get this:
>>>x = ([1, 2], [3, 4], [5, 6])
>>>L = []
>>> [L.extend(i) for i in x]
[None, None, None]
But this works fine within function:
>>> def myfunc():
x = ([1, 2], [3, 4], [5, 6])
L = []
[L.extend(i) for i in x]
print(L)
>>>myfunc()
[1, 2, 3, 4, 5, 6]
The question is why I'm getting empty list while working with comprehension
in interactive console?
Thanks for your help.
Ivan.
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