#12029: Fast conversion of ClonableIntArray to list
-----------------------------+----------------------------------------------
Reporter: SimonKing | Owner: sage-combinat
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-4.8
Component: combinatorics | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author: Simon King
Merged: | Dependencies:
-----------------------------+----------------------------------------------
Changes (by SimonKing):
* status: new => needs_review
Comment:
Replying to [comment:1 hivert]:
> - The {{{.list()}}} method is not a Python convention, it is a Sage-
Combinat (and maybe Sage) convention. Isn't it ?
Yes. But there are different places in Sage where `.list()` is used, and I
think if there is a faster way to return a list than via an iterator then
it should at least be offered.
> - Since the new Cython allows it. Did you try to define an iterator
(using yield) without relying on the list ? It could be faster.
As I stated in the ticket description: I did try, and it was not faster.
To be concrete: Here is the code that I tested.
{{{
#!python
def __iter__(self):
"""
Iterate over the items of self.
...
"""
cdef int i
for i from 0<=i<self._len:
yield self._list[i]
}}}
And here is the benchmark:
{{{
sage: from sage.structure.list_clone import IncreasingIntArrays
sage: I = IncreasingIntArrays()(range(1000))
sage: timeit("L = list(I)", number=10000)
10000 loops, best of 3: 34.3 µs per loop
}}}
> - Also I'm not sure using append to build the list is a good idea (due
to possible reallocation).
Appending to a list - if the list is cdefined - is a very quick operation
in Cython.
> Si you know the list length from the beginning, why not allocation the
list and filling it with a loop ?
Can one allocate a Python list without filling it?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12029#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
