#16868: A real difference matrix has k columns
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Reporter: ncohen | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.4
Component: combinatorial | Resolution:
designs | Merged in:
Keywords: | Reviewers:
Authors: Nathann Cohen | Work issues:
Report Upstream: N/A | Commit:
Branch: public/16868 | 361c4034247f4b3944dbb52a1259b184dfc6a250
Dependencies: #16846 | Stopgaps:
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Comment (by ncohen):
Replying to [comment:3 vdelecroix]:
> I thought it was better standardization but in
`OA_from_quasi_difference_matrix` you have
> {{{
> # Each line is expanded by [g+x for x in line for g in G] then relabeled
> # with integers. Missing values are also handled.
> new_M = []
> for line in izip(*M):
> ...
> ...
> new_M = zip(*new_M)
> }}}
> what's the point?
Well, first if you only have one "zip*" in the whole library then the
point is reached. I looked at that part of the code and I felt that the
best way to implement it required two calls to zip, but for all others
applications (functions in `database.py`) it is easier to work on this
version of the matrix, for one constantly add rows, not columns.
So even if there is a "zip*" somewhere, the rest of the code is easier to
write/read.
Nathann
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Ticket URL: <http://trac.sagemath.org/ticket/16868#comment:4>
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