gurobipy.SOS#
- class SOS#
Gurobi SOS constraint object. SOS constraints are always associated with a particular model. You create an SOS object by adding an SOS constraint to a model (using
Model.addSOS
), rather than by using an SOS constructor. Similarly, SOS constraints are removed using theModel.remove
method.An SOS constraint can be of type 1 or 2 (
GRB.SOS_TYPE1
orGRB.SOS_TYPE2
). A type 1 SOS constraint is a set of variables where at most one variable in the set may take a value other than zero. A type 2 SOS constraint is an ordered set of variables where at most two variables in the set may take non-zero values. If two take non-zero values, they must be contiguous in the ordered set.SOS constraint objects have one attribute, IISSOS, which can be queried with the
SOS.getAttr
method.- getAttr(attrname)#
Query the value of an SOS attribute. The full list of available attributes can be found in the Attributes section.
Raises an
AttributeError
if the requested attribute doesn’t exist or can’t be queried. Raises aGurobiError
if there is a problem with theSOS
object (e.g., it was removed from the model).- Parameters:
attrname – The attribute being queried.
- Returns:
The current value of the requested attribute.
- Example:
print(sos.getAttr(GRB.Attr.IISSOS))
- property index#
This property returns the current index, or order, of the SOS constraint in the underlying model.
Note that the index of an SOS constraint may change after subsequent model modifications.
- Returns:
-2: removed, -1: not in model, otherwise: index of the SOS constraint in the model
- setAttr(attrname, newvalue)#
Set the value of an SOS attribute. Note that, due to our lazy update approach, the change won’t actually take effect until you update the model (using
Model.update
), optimize the model (usingModel.optimize
), or write the model to disk (usingModel.write
).The full list of available attributes can be found in the Attributes section.
Raises an
AttributeError
if the specified attribute doesn’t exist or can’t be set. Raises aGurobiError
if there is a problem with theSOS
object (e.g., it was removed from the model).- Parameters:
attrname – The attribute being modified.
newvalue – The desired new value of the attribute.
- Example:
sos.setAttr(GRB.Attr.IISSOSForce, 1) var.setAttr("IISSOSForce", 0.0)