Efficient way to remove objects from a list

[=?GB2312?B?0rvK18qr?=]

Hi all,

Today I wrote some code like this:

for m in self.messages:
if not m.finished:
continue

#process the message

fini = [m for m in self.messages if m.finished]
for m in fini:
self.messages.r emove(m)

As you can, I want to find these finished messages in
"self.messages" ,
process them, and then remove them from the list.

Because a list can not be modified while iterating it, I have to use
a list "fini" to accomplish the target.

I found a smell of bad performance here.
Is there any faster ways?

[Peter Otten]

Re: Efficient way to remove objects from a list

Chris Rebert wrote:

On Mon, Nov 3, 2008 at 1:40 AM, 一首诗 <newptcai@gmail .comwrote:

>Hi all,
>>
>Today I wrote some code like this:
>>

>
Build a new list as you go, then overwrite the old list with it.
>
unfinished = []
>

> for m in self.messages:
> if not m.finished:

unfinished.appe nd(m)

> continue
>>
> #process the message
>>

>
Remove the following code
>

> fini = [m for m in self.messages if m.finished]
> for m in fini:
> self.messages.r emove(m)

>
self.messages[:] = unfinished

Just

self.messages = unfinished

if also OK unless you have multiple references to the self.messages list.

This way you aren't calling .remove() multiple times and only iterate
through the list once.

[=?GB2312?B?0rvK18qr?=]

Re: Efficient way to remove objects from a list

Thanks! That's a more clear way!

On Nov 3, 9:38 pm, Peter Otten <__pete...@web. dewrote:

Chris Rebert wrote:

On Mon, Nov 3, 2008 at 1:40 AM, Ò»Ê×Ê« <newpt...@gmail .com>wrote:

Hi all,

>

Today I wrote some code like this:

>

Build a new list as you go, then overwrite the old list with it.

>

unfinished = []

>

for m in self.messages:
if not m.finished:

unfinished.appe nd(m)

continue

>

#process the message

>

Remove the following code

>

fini = [m for m in self.messages if m.finished]
for m in fini:
self.messages.r emove(m)

>

self.messages[:] = unfinished

>
Just
>
self.messages = unfinished
>
if also OK unless you have multiple references to the self.messages list.
>

This way you aren't calling .remove() multiple times and only iterate
through the list once.

>
>