Fix appsi auto-update when unfixing a variable and changing its bound #2996
Conversation
pyomo/contrib/appsi/base.py
Outdated
| elif ub is not v._ub: | ||
| vars_to_update.append(v) | ||
| elif (fixed is not v.fixed) or (fixed and (value != v.value)): | ||
| if (fixed is not v.fixed) or (fixed and (value != v.value)): |
There was a problem hiding this comment.
Linters would probably prefer this to be != and not is not (because you are comparing bool). The issue is that it is possible to get POD values that compare equal, but are not the same object (so is not returns True). In this case, a false positive it fine (it just means APPSI does a little extra unnecessary work), but it might be better to make a distinction for when we care if an object changes or when the value changes.
There was a problem hiding this comment.
great point. I'll update this.
| elif lb is not v._lb: | ||
| vars_to_update.append(v) | ||
| elif ub is not v._ub: | ||
| vars_to_update.append(v) |
There was a problem hiding this comment.
This catches if the user re-assigns the lower / upper bound, but what about bounds that include mutable Params? Does changing the Param value get propagated to updated bounds?
There was a problem hiding this comment.
that should get caught on the next two lines.
There was a problem hiding this comment.
I don't think that's the case: that only catches if the domain changes, and not if the value of the bounds change:
>>> from pyomo.environ import *
>>> m = ConcreteModel()
>>> m.x = Var()
>>> m.p = Param(mutable=True, initialize=1)
>>> m.x.bounds = -m.p, m.p
>>> m.x.bounds
(-1.0, 1.0)
>>> m.x.domain.get_interval()
(None, None, 0)
>>> m.p = 5
>>> m.x.bounds
(-5.0, 5.0)
>>> m.x.domain.get_interval()
(None, None, 0)There was a problem hiding this comment.
oh, my mistake. You are right. The case of bounds with mutable parameters is actually caught with the update_params method and is handled differently for each solver. Here is how it is handled with Gurobi.
| elif domain_interval != v.domain.get_interval(): | ||
| vars_to_update.append(v) |
There was a problem hiding this comment.
right here, @jsiirola
Codecov ReportPatch coverage:
Additional details and impacted files@@ Coverage Diff @@
## main #2996 +/- ##
==========================================
+ Coverage 87.85% 88.09% +0.23%
==========================================
Files 769 769
Lines 89497 89497
==========================================
+ Hits 78632 78838 +206
+ Misses 10865 10659 -206
Flags with carried forward coverage won't be shown. Click here to find out more.
☔ View full report in Codecov by Sentry. |
Summary/Motivation:
This PR fixes a bug in appsi. The bug occurs when both unfixing a variable and changing its bound. Because of the ordering of some if statements, we were not hitting some code that we should. As a result, objectives/constraints that used the fixed variable were not getting updated correctly.
Changes proposed in this PR:
Legal Acknowledgement
By contributing to this software project, I have read the contribution guide and agree to the following terms and conditions for my contribution: