def _fix_vars(self, expr, model):
""" Walk through the S-expression, fixing variables. """
if expr._args is None:
return expr
_args = []
for i in range(len(expr._args)):
if isinstance(expr._args[i], _ExpressionBase):
_args.append(self._fix_vars(expr._args[i], model))
elif (isinstance(expr._args[i], Var) or isinstance(
expr._args[i], _VarData)) and expr._args[i].fixed:
if expr._args[i].value != 0.0:
_args.append(
NumericConstant(None, None, expr._args[i].value))
else:
_args.append(expr._args[i])
expr._args = _args
return expr
def _transform_disjunct(self, obj, transBlock, varSet, localVars):
if hasattr(obj, "_gdp_transformation_info"):
infodict = obj._gdp_transformation_info
# If the user has something with our name that is not a dict, we
# scream. If they have a dict with this name then we are just going
# to use it...
if type(infodict) is not dict:
raise GDP_Error(
"Disjunct %s contains an attribute named "
"_gdp_transformation_info. The transformation requires "
"that it can create this attribute!" % obj.name)
else:
infodict = obj._gdp_transformation_info = {}
# deactivated means either we've already transformed or user deactivated
if not obj.active:
if obj.indicator_var.is_fixed():
if value(obj.indicator_var) == 0:
# The user cleanly deactivated the disjunct: there
# is nothing for us to do here.
return
else:
raise GDP_Error(
"The disjunct %s is deactivated, but the "
"indicator_var is fixed to %s. This makes no sense." %
(obj.name, value(obj.indicator_var)))
if not infodict.get('relaxed', False):
raise GDP_Error(
"The disjunct %s is deactivated, but the "
"indicator_var is not fixed and the disjunct does not "
"appear to have been relaxed. This makes no sense." %
(obj.name, ))
if 'chull' in infodict:
# we've transformed it (with CHull), so don't do it again.
return
# add reference to original disjunct to info dict on
# transformation block
relaxedDisjuncts = transBlock.relaxedDisjuncts
relaxationBlock = relaxedDisjuncts[len(relaxedDisjuncts)]
relaxationBlockInfo = relaxationBlock._gdp_transformation_info = {
'src': obj,
'srcVars': ComponentMap(),
'srcConstraints': ComponentMap(),
'boundConstraintToSrcVar': ComponentMap(),
}
infodict['chull'] = chull = {
'relaxationBlock': relaxationBlock,
'relaxedConstraints': ComponentMap(),
'disaggregatedVars': ComponentMap(),
'bigmConstraints': ComponentMap(),
}
# if this is a disjunctData from an indexed disjunct, we are
# going to want to check at the end that the container is
# deactivated if everything in it is. So we save it in our
# dictionary of things to check if it isn't there already.
disjParent = obj.parent_component()
if disjParent.is_indexed() and \
disjParent not in transBlock.disjContainers:
transBlock.disjContainers.add(disjParent)
# add the disaggregated variables and their bigm constraints
# to the relaxationBlock
for var in varSet:
lb = var.lb
ub = var.ub
if lb is None or ub is None:
raise GDP_Error("Variables that appear in disjuncts must be "
"bounded in order to use the chull "
"transformation! Missing bound for %s." %
(var.name))
disaggregatedVar = Var(within=Reals,
bounds=(min(0, lb), max(0, ub)),
initialize=var.value)
# naming conflicts are possible here since this is a bunch
# of variables from different blocks coming together, so we
# get a unique name
disaggregatedVarName = unique_component_name(
relaxationBlock, var.local_name)
relaxationBlock.add_component(disaggregatedVarName,
disaggregatedVar)
chull['disaggregatedVars'][var] = disaggregatedVar
relaxationBlockInfo['srcVars'][disaggregatedVar] = var
bigmConstraint = Constraint(transBlock.lbub)
relaxationBlock.add_component(disaggregatedVarName + "_bounds",
bigmConstraint)
if lb:
bigmConstraint.add('lb',
obj.indicator_var * lb <= disaggregatedVar)
if ub:
bigmConstraint.add('ub',
disaggregatedVar <= obj.indicator_var * ub)
chull['bigmConstraints'][var] = bigmConstraint
relaxationBlockInfo['boundConstraintToSrcVar'][
bigmConstraint] = var
for var in localVars:
lb = var.lb
ub = var.ub
if lb is None or ub is None:
raise GDP_Error("Variables that appear in disjuncts must be "
"bounded in order to use the chull "
"transformation! Missing bound for %s." %
(var.name))
if value(lb) > 0:
var.setlb(0)
if value(ub) < 0:
var.setub(0)
# naming conflicts are possible here since this is a bunch
# of variables from different blocks coming together, so we
# get a unique name
conName = unique_component_name(relaxationBlock,
var.local_name + "_bounds")
bigmConstraint = Constraint(transBlock.lbub)
relaxationBlock.add_component(conName, bigmConstraint)
bigmConstraint.add('lb', obj.indicator_var * lb <= var)
bigmConstraint.add('ub', var <= obj.indicator_var * ub)
chull['bigmConstraints'][var] = bigmConstraint
relaxationBlockInfo['boundConstraintToSrcVar'][
bigmConstraint] = var
var_substitute_map = dict(
(id(v), newV) for v, newV in iteritems(chull['disaggregatedVars']))
zero_substitute_map = dict(
(id(v), NumericConstant(0))
for v, newV in iteritems(chull['disaggregatedVars']))
zero_substitute_map.update(
(id(v), NumericConstant(0)) for v in localVars)
# Transform each component within this disjunct
self._transform_block_components(obj, obj, infodict,
var_substitute_map,
zero_substitute_map)
# deactivate disjunct so we know we've relaxed it
obj._deactivate_without_fixing_indicator()
infodict['relaxed'] = True