lists, performance..

gabor gabor at realtime.sk
Thu Oct 31 14:49:53 CET 2002


hi,

i'm working on a graphic application ( python + opengl)..

and i have some lists of vertices... but that's not important..

let's say a have loooooooong ( long = 500 to 5000 ) lists of relatively
simple objects..

2 questions:

1. is a list implemented as a vector? i mean looking up the n-th element
is done in o[1] (constant time)?

2. i want to insert several lists into a big list.. better to say i want
to concatenate them... but i don't really like the 'extent' method,
because i want to do a deep-copy... for example:
list1 = [ ['a','b','c'], [1,2,3,4] ,[5,6,7]]
list2 = []
list2.extend(list1)
but now if i modify an element in list1, list2 gets modified too..
for now i'm doing:

list1 = ...
list2 = ...

for item in list2:
	list1.append(item)

but maybe this is too slow.. or isn't? ideally i'd like to have
something like reserve in c++....
so let's say i have a list which len() is 30. now i want to insert
20elements... wouldn't it be faster to somehow resize the list directly
to 50, and then add the elements?
i'm worried about how many times would the list resize itself to be able
to contain the additional 20elements if i would add them one-by-one

thanks,
gabor
-- 
listening to gits2-from-avi-intro
gpg key at www.keyserver.net
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