#10530: De Bruijn Sequence construction for combinat
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Reporter: eviatarbach | Owner: sage-combinat
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-4.6.1
Component: combinatorics | Keywords:
Author: Eviatar Bach | Upstream: N/A
Reviewer: Nicolas M. Thiéry | Merged:
Work_issues: |
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Comment(by eviatarbach):
Thank you for the comments. I have a few questions:
''Rather than defining an attribute self.k_is_alphabet, I would setup two
attributes self.k and self.alphabet once for all in the init. Then no more
branching needs to be done later on.''
I know it looks ugly. The point of having k_is_alphabet is to check
whether the input ''k'' is an alphabet or an arity, as the processing is
different in either case. I was thinking of removing the alphabet
functionality; maybe just the arity would suffice? One could always map
values onto the digits after.
''The length of the sequence is known in advance, right? Then it should be
faster to allocate a bit list right away, and then fill it up, rather than
using append.''
I'm not clear on this. Are you suggesting I compute the length of the
array in advance, create ''sequence'' full of zeros to that length, and
then use indeces to change the values? Is append that much slower that
creating a long list and then filling it would be faster?
Or are you suggesting that I declare sequence as an int array in C, then
fill it? This was my initial idea, but I couldn't find a way to insert
arguments into the declaration. This returns a traceback:
cdef sequence[k^n]
Thanks again!
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10530#comment:4>
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