On 24/03/2016 15:03, Jon Ribbens wrote:
On 2016-03-24, BartC <b...@freeuk.com> wrote:
On 24/03/2016 14:08, Jon Ribbens wrote:
if you thought you needed to do that then most likely what you
should actually be doing is re-writing your code so you no longer
need to. However, you could do:
L[:] = [0] * len(L)
OK, but that's just building a new list as I've already mentioned.
No it isn't, it's replacing the elements in-place,
Replace them with what, if not an entirely new list built from
'[0]*len(L)'? (And which would briefly require twice the memory occupied
by the old list, if I'm not mistaken.)
Or is the Pythonic way, when you want to change some elements of a list
to just build a new one that incorporates those changes?
I think it would depend on how many elements you were changing and
why. It doesn't come up all that often because of the ease in which
Python functions can return multiple values but sometimes you might
make a function which takes as a parameter a list which the function
will mutate.
Answering my own question, obviously changing some elements of a list
has to be Pythonic, otherwise there wouldn't be lists, only non-mutable
tuples. Although I was talking more within the context of a for-in loop.
--
Bartc
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