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MConstr
Gurobi matrix constraint object. An MConstr object is an array-like
data structure that represents multiple linear constraints (in contrast
to a Constr object, which represents a single
constraint). It behaves similar to NumPy's ndarrays, e.g., it has a
shape and can be indexed and sliced. Matrix constraints are always associated
with a particular model. You typically create these objects with
Model.addConstr, using overloaded
comparison operators on matrix variables and
linear matrix expressions, or with the
method Model.addMConstr.
Constraint objects have a number of attributes. The full list can be found in the Attributes section of this document. Some constraint attributes can only be queried, while others can also be set. Recall that the Gurobi optimizer employs a lazy update approach, so changes to attributes don't take effect until the next call to Model.update, Model.optimize, or Model.write on the associated model.
We should point out a few things about constraint attributes. Consider the
rhs attribute. The values for a matrix constraint mc can be
queried using mc.rhs. The Gurobi library ignores letter case in
attribute names, so it can also be queried as mc.RHS. Attribute
values are returned as a NumPy ndarray that has the same shape as
mc. An attribute can be set, using a standard assignment statement (e.g.,
constr.rhs = b), with b being either an ndarray with
the appropriate shape, or a scalar
which is then applied to all of the associated constraints. However, as mentioned
earlier, attribute modification is done in a lazy fashion, so you won't see the
effect of the change immediately. And some attributes can not be set (e.g.,
the Pi attribute), so attempts to assign new values to them will raise
an exception.
You can also use MConstr.getAttr/
MConstr.setAttr to access
attributes. The attribute name can be passed to these routines as a
string, or you can use the constants defined in the
GRB.Attr class (e.g.,
GRB.Attr.RHS).
Subsections
