#12014: Make linearcode.__iter__ and linearcode.list() faster
-----------------------------+----------------------------------------------
Reporter: ppurka | Owner: wdj
Type: enhancement | Status: new
Priority: minor | Milestone: sage-4.8
Component: coding theory | Keywords: linear code, iter
Work_issues: | Upstream: N/A
Reviewer: | Author: Radoslav Kirov, Punarbasu
Purkayastha
Merged: | Dependencies:
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The `__iter__()` method in `devel/sage/sage/coding/linear_code.py` tries
to return the codewords standard form of the code. Is there a reason why
it does so? This should be left to the gen_mat to provide a systematic
generator matrix.
The `list()` method on the other hand doesn't call `__iter__()` at all. It
instead calls a more generic method which is actually quite slow. (See
[https://groups.google.com/d/msg/sage-devel/wmaSLdlkn-c/3Nu8Kx8DKZMJ a
short discussion in sage-devel])
I am attaching a patch which makes it faster and makes `list()` call
`__iter__()`. This patch is simply to show you that the methods can be
faster. So, I haven't done any doctests. Some tests will probably break
because the order of codewords returned are not the same as earlier.
Before going ahead and trying to fix doctests, etc, I want to be sure that
this patch is desirable.
As for the speedup, here is an example. The functions in Sage are the
unpatched versions. `list_codewords()` is a function implemented in the
file that is loaded with `load( )` and this contains the `iterate()`
method present in the patch.
{{{
...ding_Theory/programs/sage> ~/Installations/sage-4.7.2/sage
----------------------------------------------------------------------
| Sage Version 4.7.2, Release Date: 2011-10-29 |
| Type notebook() for the GUI, and license() for information. |
----------------------------------------------------------------------
sage: C = ReedSolomonCode(7, 3, GF(8, 'a'))
sage: load('code_functions.py')
sage: timeit('list(C.__iter__())')
5 loops, best of 3: 90.9 ms per loop
sage: timeit('C.list()')
5 loops, best of 3: 122 ms per loop
sage: timeit('list_codewords(C)') # new code implemented in list_codewords
125 loops, best of 3: 1.66 ms per loop
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12014>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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