#15862: Mutability of tableaux, for the n-th time
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Reporter: darij | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.2
Component: combinatorics | Resolution:
Keywords: tableaux, sage-combinat, | Merged in:
mutability | Reviewers:
Authors: | Work issues:
Report Upstream: N/A | Commit:
Branch: | Stopgaps:
Dependencies: |
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Comment (by darij):
`t = map(tuple, t)` sounds like a good idea to me. The immutability of the
outer list is handled by `CombinatorialObject`, so we only need to care
about the inner ones.
Is `_repr_` slowdown important? That is, is `_repr_` used in any non-IO
contexts such as hashing and caching? (I know it sometimes is; the
question whether it is here.)
Is `_repr_` the only thing that gets slowed down if we replace the (inner)
lists by tuples? I'd say it should be, because any method on tableaux that
needs to mess around with rows as lists currently needs to clone them
before doing so, and experiments tell me that `t[:]` is considerably
faster when `t` is a tuple than when `t` is a list:
{{{
sage: g = tuple(range(15))
sage: %timeit g[:]
10000000 loops, best of 3: 73.4 ns per loop
sage: g = range(15)
sage: %timeit g[:]
1000000 loops, best of 3: 197 ns per loop
sage: g = tuple(range(3))
sage: %timeit g[:]
10000000 loops, best of 3: 73.4 ns per loop
sage: g = range(3)
sage: %timeit g[:]
10000000 loops, best of 3: 158 ns per loop
}}}
***
This might and not might be related, but do you have any idea where the
slowdowns in http://trac.sagemath.org/ticket/14711#comment:107 come from?
(I'm aware that running all doctests in series is not the scientific way
of assessing performance, but I'm still worried about tableaux getting
slower...)
--
Ticket URL: <http://trac.sagemath.org/ticket/15862#comment:5>
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