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Why can't you assign to a list in a loop without enumerate?

In the following code snippet, I attempt to assign 10 to every index in
the list a and fail because when I try to assign number to 10, number
is a deep copy of the ith index (is this statement correct?).
>>a = [1,2,3,4,5]
for number in a:
.... number = 10
[1, 2, 3, 4, 5]

So, I have to resort to using enumerate to assign to the list:
>>for i, number in enumerate(a):
.... a[i] = 10
[10, 10, 10, 10, 10]

My question is, what was the motivation for returning a deep copy of
the value at the ith index inside a for loop instead of the value
itself? Also, is there any way to assign to a list in a for loop (with
as little code as used above) without using enumerate?



Oct 31 '06
12 2111
Fredrik Lundh wrote:
define "it".
Sorry! I mean iterating over a list and having the list index
available in the loop. Like:

for i, thing in enumerate(thing s):


BOFH excuse #254:

Interference from lunar radiation

Nov 1 '06 #11
Bjoern Schliessmann wrote:
>define "it".

Sorry! I mean iterating over a list and having the list index
available in the loop. Like:

for i, thing in enumerate(thing s):
"enumerate" is the obviously right thing for this, sure. but it's not
necessarily the right thing for the OP's "I want to create a new list
based on an existing list". modifying the existing list is usually not
the most efficient way to do that.


Nov 1 '06 #12
Fredrik Lundh wrote:
"enumerate" is the obviously right thing for this, sure.
but it's not necessarily the right thing for the OP's "I want to
create a new list based on an existing list". modifying the
existing list is usually not the most efficient way to do that.


BOFH excuse #418:

Sysadmins busy fighting SPAM.

Nov 1 '06 #13

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