Opened 4 years ago
Last modified 3 years ago
#20656 needs_info enhancement
MixedIntegerLinearProgram: Remove _variables dictionary
Reported by: | mkoeppe | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-7.3 |
Component: | numerical | Keywords: | lp |
Cc: | nbruin, dimpase, vdelecroix, jdemeyer, chapoton | Merged in: | |
Authors: | Matthias Koeppe | Reviewers: | |
Report Upstream: | N/A | Work issues: | |
Branch: | u/mkoeppe/mixedintegerlinearprogram__remove__variables_dictionary (Commits) | Commit: | b7906ffd31c2007d81cb556d23b8b814d2faaebb |
Dependencies: | #20461, #20462 | Stopgaps: |
Description
The '_variables' attribute dictionary maps a "variable" (an "element" of a MIPVariable
"dictionary") to an index in the backend. This is redundant because these "variables" are elements of type LinearFunction
, and as such know their index in the backend already.
sage: p = MixedIntegerLinearProgram(solver='GLPK') sage: pv = p.new_variable(nonnegative=True) sage: pv[0] x_0 sage: pv[77] x_1 sage: pv[0].dict().keys() [0] sage: pv[77].dict().keys() [1]
Change History (4)
comment:1 Changed 4 years ago by
- Branch set to u/mkoeppe/mixedintegerlinearprogram__remove__variables_dictionary
comment:2 Changed 4 years ago by
- Cc chapoton added
- Commit set to b7906ffd31c2007d81cb556d23b8b814d2faaebb
- Status changed from new to needs_review
comment:3 Changed 3 years ago by
- Status changed from needs_review to needs_info
Needs a rebase. However, I'm worried this could cause a speed regression as a dict
lookup is a system python call whereas you are now doing a number of python function calls. Also storing a (relatively?) small dict
doesn't cost much memory I would think.
comment:4 Changed 3 years ago by
I haven't done any timings regarding this patch.
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New commits:
MixedIntegerLinearProgram._linear_variable_index: New
MixedIntegerLinearProgram: Remove _variables