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....just bit me in the "fuzzy posterior". The best I can come up with
is the hideous

lol = [[] for _ in xrange(500)]

Is there something better? What did one do before comprehensions
were available? I suppose in that case one would have to go all
the way with

lol = [None] * 500
for i in xrange(len(lol)):
lol[i] = []

Yikes. 10 miles uphill, both ways...

kynn

On 13 Nov, 21:26, kj <no.em...@please.post> wrote:
> ...just bit me in the "fuzzy posterior". *The best I can come up with
> is the hideous
>
> * lol = [[] for _ in xrange(500)]
>
> Is there something better? *

That's generally the accepted way of creating a LOL.

> What did one do before comprehensions
> were available? *I suppose in that case one would have to go all
> the way with
>
> * lol = [None] * 500
> * for i in xrange(len(lol)):
> * * * lol[i] = []
>
> Yikes. *10 miles uphill, both ways...
>

>>> lol = map(lambda L: [], xrange(5))
>>> [id(i) for i in lol]
[167614956, 167605004, 167738060, 167737996, 167613036]

Jon.

In <6e20a31b-2218-49c5-a32c-> Jon Clements <> writes:

>>>> lol =3D map(lambda L: [], xrange(5))
>>>> [id(i) for i in lol]
>[167614956, 167605004, 167738060, 167737996, 167613036]

Oh yeah, map! I'd forgotten all about it. Thanks!

kynn

kj schrieb:
> ...just bit me in the "fuzzy posterior". The best I can come up with
> is the hideous
>
> lol = [[] for _ in xrange(500)]

If you call that hideous, I suggest you perform the same exercise in
Java or C++ - and then come back to python and relax....


Diez

kj <> writes:
> lol = [None] * 500
> for i in xrange(len(lol)):
> lol[i] = []

lol = map(list, [()] * 500)

2009/11/14 Brian J Mingus <>:
>
>
> On Sat, Nov 14, 2009 at 1:50 AM, Paul Rubin <http://>
> wrote:
>>
>> kj <> writes:
>> > * lol = [None] * 500
>> > * for i in xrange(len(lol)):
>> > * * * lol[i] = []
>>
>> lol = map(list, [()] * 500)
>
> Could someone explain what the deal is with this thread? Thanks.
> [[]]*500
>

Try
>>> lst=[[]]*500
>>> lst[7].append(2)
>>> lst
to see...

vbr

Diez B. Roggisch wrote:
> kj schrieb:
>> lol = [[] for _ in xrange(500)]
>
> If you call that hideous, I suggest you perform the same exercise in
> Java or C++ - and then come back to python and relax....

I might be missing something that's not explicitly mentioned here, but I'd
say that all non-associative containers in C++ have a resize() method, some
even taking an initial size in their constructor.

That said, [[]]*500 is IMHO more readable.

Uli

Ulrich Eckhardt <> writes:
> That said, [[]]*500 is IMHO more readable.

But the issue in the thread is that it does the wrong thing.

On Fri, 13 Nov 2009 21:26:01 +0000, kj wrote:

> ...just bit me in the "fuzzy posterior".

It's not a bug. Just because it doesn't behave as you would like it to
behave doesn't mean it isn't behaving as designed.


> The best I can come up with is the hideous
>
> lol = [[] for _ in xrange(500)]

That's not hideous.


> Is there something better? What did one do before comprehensions were
> available? I suppose in that case one would have to go all the way with
>
> lol = [None] * 500
> for i in xrange(len(lol)):
> lol[i] = []
>
> Yikes. 10 miles uphill, both ways...

What's wrong with that?


lol = []
for _ in xrange(500): lol.append([])


is a simple alternative too, although the list comp is better.


--
Steven