def _Combine(port, name, index_set):
port_parent = port.parent_block()
var = port.vars[name]
in_vars = []
sources = port.sources(active=True)
if not len(sources):
return in_vars
if len(sources) == 1 and len(sources[0].source.dests(active=True)) == 1:
# This is a 1-to-1 connection, no need for evar, just equality.
arc = sources[0]
Port._add_equality_constraint(arc, name, index_set)
return in_vars
for arc in sources:
eblock = arc.expanded_block
# Make and record new variables for every arc with this member.
evar = Port._create_evar(port.vars[name], name, eblock, index_set)
in_vars.append(evar)
# Create constraint: var == sum of evars
# Same logic as Port._Split
cname = unique_component_name(port_parent, "%s_%s_insum" %
(alphanum_label_from_name(port.local_name), name))
def rule(m, *args):
if len(args):
return sum(evar[args] for evar in in_vars) == var[args]
else:
return sum(evar for evar in in_vars) == var
con = Constraint(index_set, rule=rule)
port_parent.add_component(cname, con)
return in_vars
def _Split(port, name, index_set, include_splitfrac=False,
write_var_sum=True):
port_parent = port.parent_block()
var = port.vars[name]
out_vars = []
no_splitfrac = False
dests = port.dests(active=True)
if not len(dests):
return out_vars
if len(dests) == 1:
# No need for splitting on one outlet.
# Make sure they do not try to fix splitfrac not at 1.
splitfracspec = port.get_split_fraction(dests[0])
if splitfracspec is not None:
if splitfracspec[0] != 1 and splitfracspec[1] == True:
raise ValueError(
"Cannot fix splitfrac not at 1 for port '%s' with a "
"single dest '%s'" % (port.name, dests[0].name))
no_splitfrac = True
if len(dests[0].destination.sources(active=True)) == 1:
# This is a 1-to-1 connection, no need for evar, just equality.
arc = dests[0]
Port._add_equality_constraint(arc, name, index_set)
return out_vars
for arc in dests:
eblock = arc.expanded_block
# Make and record new variables for every arc with this member.
evar = Port._create_evar(port.vars[name], name, eblock, index_set)
out_vars.append(evar)
if no_splitfrac:
continue
# Create and potentially initialize split fraction variables.
# This function will be called for every Extensive member of this
# port, but we only need one splitfrac variable per arc, so check
# if it already exists before making a new one. However, we do not
# need a splitfrac if there is only one Extensive data object,
# so first check whether or not we need it.
if eblock.component("splitfrac") is None:
if not include_splitfrac:
num_data_objs = 0
for k, v in iteritems(port.vars):
if port.is_extensive(k):
if v.is_indexed():
num_data_objs += len(v)
else:
num_data_objs += 1
if num_data_objs > 1:
break
if num_data_objs <= 1:
# Do not make splitfrac, do not make split constraints.
# Make sure they didn't specify splitfracs.
# This inner loop will only run once.
for arc in dests:
if port.get_split_fraction(arc) is not None:
raise ValueError(
"Cannot specify splitfracs for port '%s' "
"(found arc '%s') because this port only "
"has one variable. To have control over "
"splitfracs, please pass the "
" include_splitfrac=True argument." %
(port.name, arc.name))
no_splitfrac = True
continue
eblock.splitfrac = Var()
splitfracspec = port.get_split_fraction(arc)
if splitfracspec is not None:
eblock.splitfrac = splitfracspec[0]
if splitfracspec[1]:
eblock.splitfrac.fix()
# Create constraint for this member using splitfrac.
cname = "%s_split" % name
def rule(m, *args):
if len(args):
return evar[args] == eblock.splitfrac * var[args]
else:
return evar == eblock.splitfrac * var
con = Constraint(index_set, rule=rule)
eblock.add_component(cname, con)
if write_var_sum:
# Create var total sum constraint: var == sum of evars
# Need to alphanum port name in case it is indexed.
cname = unique_component_name(port_parent, "%s_%s_outsum" %
(alphanum_label_from_name(port.local_name), name))
def rule(m, *args):
if len(args):
return sum(evar[args] for evar in out_vars) == var[args]
else:
return sum(evar for evar in out_vars) == var
con = Constraint(index_set, rule=rule)
port_parent.add_component(cname, con)
else:
# OR create constraint on splitfrac vars: sum == 1
if no_splitfrac:
raise ValueError(
"Cannot choose to write split fraction sum constraint for "
"ports with a single destination or a single Extensive "
"variable.\nSplit fractions are skipped in this case to "
"simplify the model.\nPlease use write_var_sum=True on "
"this port (the default).")
cname = unique_component_name(port_parent,
"%s_frac_sum" % alphanum_label_from_name(port.local_name))
con = Constraint(expr=
sum(a.expanded_block.splitfrac for a in dests) == 1)
port_parent.add_component(cname, con)
return out_vars
