def remove_subgraph(self, name):
"""Remove subgraph with given name."""
try:
handle=gv.agsubg(self.handle,name,_Action.find)
except TypeError:
raise TypeError("Subgraph name must be a string: %s"%name)
if handle is None:
raise KeyError("Subgraph %s not in graph."%name)
gv.agdelsubg(self.handle,handle)
def get_subgraph(self,name):
"""Return existing subgraph with specified name or None if it
doesn't exist.
"""
try:
handle=gv.agsubg(self.handle,name,_Action.find)
except TypeError:
raise TypeError("Subgraph name must be a string: %s"%name)
if handle is None: return None
H=self.__class__(strict=self.strict,
directed=self.directed,
handle=handle)
return H
def add_subgraph(self, nbunch=None, name=None, **attr):
"""Return subgraph induced by nodes in nbunch.
"""
try:
handle=gv.agsubg(self.handle,name,_Action.create)
except TypeError:
raise TypeError("Subgraph name must be a string: %s"%name)
H=self.__class__(strict=self.strict,
directed=self.directed,
handle=handle,name=name,**attr)
if nbunch is None: return H
# add induced subgraph on nodes in nbunch
bunch=self.prepare_nbunch(nbunch)
H.add_nodes_from(bunch)
for (u,v) in self.edges():
if u in H and v in H:
H.add_edge(u,v)
return H
