Reference

(function from pyomo.core.base.reference)

pyomo.core.base.reference.Reference(reference, ctype=NOTSET)[source]

Creates a component that references other components

Reference generates a reference component; that is, an indexed component that does not contain data, but instead references data stored in other components as defined by a component slice. The ctype parameter sets the Component.type() of the resulting indexed component. If the ctype parameter is not set and all data identified by the slice (at construction time) share a common Component.type(), then that type is assumed. If either the ctype parameter is None or the data has more than one ctype, the resulting indexed component will have a ctype of IndexedComponent.

If the indices associated with wildcards in the component slice all refer to the same Set objects for all data identified by the slice, then the resulting indexed component will be indexed by the product of those sets. However, if all data do not share common set objects, or only a subset of indices in a multidimentional set appear as wildcards, then the resulting indexed component will be indexed by a SetOf containing a _ReferenceSet for the slice.

Parameters:

reference (IndexedComponent_slice) – component slice that defines the data to include in the Reference component
ctype (type [optional]) – the type used to create the resulting indexed component. If not specified, the data’s ctype will be used (if all data share a common ctype). If multiple data ctypes are found or type is None, then IndexedComponent will be used.

Examples

>>> from pyomo.environ import *
>>> m = ConcreteModel()
>>> @m.Block([1,2],[3,4])
... def b(b,i,j):
...     b.x = Var(bounds=(i,j))
...
>>> m.r1 = Reference(m.b[:,:].x)
>>> m.r1.pprint()
r1 : Size=4, Index={1, 2}*{3, 4}, ReferenceTo=b[:, :].x
    Key    : Lower : Value : Upper : Fixed : Stale : Domain
    (1, 3) :     1 :  None :     3 : False :  True :  Reals
    (1, 4) :     1 :  None :     4 : False :  True :  Reals
    (2, 3) :     2 :  None :     3 : False :  True :  Reals
    (2, 4) :     2 :  None :     4 : False :  True :  Reals

Reference components may also refer to subsets of the original data:

>>> m.r2 = Reference(m.b[:,3].x)
>>> m.r2.pprint()
r2 : Size=2, Index={1, 2}, ReferenceTo=b[:, 3].x
    Key : Lower : Value : Upper : Fixed : Stale : Domain
      1 :     1 :  None :     3 : False :  True :  Reals
      2 :     2 :  None :     3 : False :  True :  Reals

Reference components may have wildcards at multiple levels of the model hierarchy:

>>> m = ConcreteModel()
>>> @m.Block([1,2])
... def b(b,i):
...     b.x = Var([3,4], bounds=(i,None))
...
>>> m.r3 = Reference(m.b[:].x[:])
>>> m.r3.pprint()
r3 : Size=4, Index=ReferenceSet(b[:].x[:]), ReferenceTo=b[:].x[:]
    Key    : Lower : Value : Upper : Fixed : Stale : Domain
    (1, 3) :     1 :  None :  None : False :  True :  Reals
    (1, 4) :     1 :  None :  None : False :  True :  Reals
    (2, 3) :     2 :  None :  None : False :  True :  Reals
    (2, 4) :     2 :  None :  None : False :  True :  Reals

The resulting reference component may be used just like any other component. Changes to the stored data will be reflected in the original objects:

>>> m.r3[1,4] = 10
>>> m.b[1].x.pprint()
x : Size=2, Index={3, 4}
    Key : Lower : Value : Upper : Fixed : Stale : Domain
      3 :     1 :  None :  None : False :  True :  Reals
      4 :     1 :    10 :  None : False : False :  Reals