def edges_():
'''
edges(<Graph>, [<nbunch>]) returns Python list of edges incident to nodes in nbunch
- If <nbunch> is not provided or None, return all edges in <Graph>
'''
g = Graph([(1, 5), (5, 5)])
g.add_edge(2, 4)
g.add_edge(1, 2)
# 2 is connected to 4 and 1, so return those edges
print(function.edges(g, 2)) # [(2, 4), (2, 1)]
# With no <nbunch>, return all edges
print(function.edges(g)) # [(1, 5), (1, 2), (5, 5), (2, 4)]
def add_edge(self, u, v=None):
if v is None: (u,v)=u # no v given, assume u is an edge tuple
if self.has_edge(u,v): return # no parallel edges allowed
elif u in self and v in self:
raise NetworkXError("adding edge %s-%s not allowed in tree"%(u,v))
elif u in self or v in self:
Graph.add_edge(self,u,v)
return
elif len(self.adj)==0: # first leaf
Graph.add_edge(self,u,v)
return
else:
raise NetworkXError("adding edge %s-%s not allowed in tree"%(u,v))
def add_edge(self, u, v=None):
if v is None: (u, v) = u # no v given, assume u is an edge tuple
if self.has_edge(u, v): return # no parallel edges allowed
elif u in self and v in self:
raise NetworkXError("adding edge %s-%s not allowed in tree" %
(u, v))
elif u in self or v in self:
Graph.add_edge(self, u, v)
return
elif len(self.adj) == 0: # first leaf
Graph.add_edge(self, u, v)
return
else:
raise NetworkXError("adding edge %s-%s not allowed in tree" %
(u, v))
def add_edge_():
'''
- <Graph>.edge[<u>][<v>] no longer exists, so use <Graph>.edges[<u>, <v>]
- Unlike v1.11 which accepted a dict as a third argument, only additionals kwargs are accepted after <u> and <v>
- The rules for arbitrary attributes are the same as v1.11 (see notes below)
'''
g = Graph([(1, 5), (5, 5)])
g.edges[1, 5]['foo'] = 'bar'
#g.add_edge(1, 5, {}) # TypeError
# This is wrong. Don't do this!
#g.add_edge(1, 5, attr_dict={})
#print(g.edges[1, 5]) # {'foo': 'bar', 'attr_dict': {}}
# A duplciate edge cannot remove existing arbitrary edge attributes
g.add_edge(1, 5)
print(g.edges[1, 5]) # {'foo': 'bar'}
def add_edge():
'''
- Adding an edge with nonexistent nodes creates those nodes
- Adding a duplicate edge can update the arbitrary attribute data for that edge (see below)
- The rules for updating arbitrary attributes are the same as those for adding a duplicate node
'''
g = Graph([(1, 5), (5, 5)])
g.edge[1][5]['foo'] = 'bar'
# A duplciate edge cannot remove existing arbitrary edge attributes.
# - Also, {} and attr_dict={} are equivalent
#g.add_edge(1, 5, attr_dict={})
#g.add_edge(1, 5, {})
#print(g.edge[1][5]) # {'foo': 'bar'}
# A duplicate edge can overwrite existing arbitrary edge attributes
#g.add_edge(1, 5, attr_dict={'foo': 'fru'})
g.add_edge(1, 5, foo='fru')
print(g.edge[1][5]) # {'foo': 'fru'}
def make_nonmultigraph(multigraph):
"""
Removes duplicate edges. Instead of having multiple edges going from the same source to the same target,
this function adds one edge with a weight attribute,
Parameters:
multigraph: The multi-graph with multi-edges
Return:
G: A new graph which is equivalent to the multi-graph.
"""
G = Graph()
for node in multigraph.nodes_iter():
G.add_node(node)
for edge in multigraph.edges_iter():
for existing_edge in G.edges_iter():
if existing_edge[0] == edge[0] and existing_edge[1] == edge[1]: #If the edge is already in the existing edge list...
G.edge[edge[0]][edge[1]]['weight'] += 1 # the existing edge's weight is incremented
G.add_edge(edge[0], edge[1], weight=1)
return G
def make_nonmultigraph(multigraph):
"""
Removes duplicate edges. Instead of having multiple edges going from the same source to the same target,
this function adds one edge with a weight attribute,
Parameters:
multigraph: The multi-graph with multi-edges
Return:
G: A new graph which is equivalent to the multi-graph.
"""
G = Graph()
for node in multigraph.nodes_iter():
G.add_node(node)
for edge in multigraph.edges_iter():
for existing_edge in G.edges_iter():
if existing_edge[0] == edge[0] and existing_edge[1] == edge[
1]: #If the edge is already in the existing edge list...
G.edge[edge[0]][edge[1]][
'weight'] += 1 # the existing edge's weight is incremented
G.add_edge(edge[0], edge[1], weight=1)
return G
def _check_cycle(mode_declarations):
g = Graph().to_directed()
for decl in mode_declarations:
input_args = decl.input_arguments()
output_args = decl.output_arguments()
for o in output_args:
g.add_node(o.name)
for i in input_args:
g.add_node(i.name)
for o in output_args:
g.add_edge(i.name, o.name)
try:
res = find_cycle(g)
except NetworkXNoCycle:
return
raise CheckFailed('Cycle found: %s' % str(res))
def add_edge(self, u, v=None):
if v is None:
(u,v)=u # no v given, assume u is an edge tuple
if self.has_edge(u,v): # no parallel edges
return
elif u in self and v in self:
raise NetworkXError, "adding edge %s-%s not allowed in tree"%(u,v)
elif u in self:
Graph.add_edge(self,u,v)
self.par[v]=u
return
elif v in self:
Graph.add_edge(self,u,v)
self.par[u]=v
return
elif len(self.adj)==0: # first leaf
Graph.add_edge(self,u,v)
self.par[v]=u # u is v's parent
return
else:
raise NetworkXError, "adding edge %s-%s not allowed in tree"%(u,v)
def add_edge(self, u, v=None):
if v is None: (u,v)=u # no v given, assume u is an edge tuple
if self.has_edge(u,v): return # no parallel edges
if u in self: # u is in forest
if v in self: # v is in forest
if self.comp[u]==self.comp[v]: # same tree?
raise NetworkXError, \
"adding edge %s-%s not allowed in forest"%(u,v)
else: # join two trees
Graph.add_edge(self,u,v)
ucomp=self.comp[u]
# set component number of v tree to u tree
for n in component.node_connected_component(self,v):
self.comp[n]=ucomp
else: # add u-v to tree in component with u
Graph.add_edge(self,u,v)
self.comp[v]=self.comp[u]
else: # make new tree with only u-v
Graph.add_edge(self,u,v)
self.comp[u]=self.nc
self.comp[v]=self.nc
self.nc+=1
def add_edge(self, u, v=None):
if v is None: (u, v) = u # no v given, assume u is an edge tuple
if self.has_edge(u, v): return # no parallel edges
if u in self: # u is in forest
if v in self: # v is in forest
if self.comp[u] == self.comp[v]: # same tree?
raise NetworkXError, \
"adding edge %s-%s not allowed in forest"%(u,v)
else: # join two trees
Graph.add_edge(self, u, v)
ucomp = self.comp[u]
# set component number of v tree to u tree
for n in component.node_connected_component(self, v):
self.comp[n] = ucomp
else: # add u-v to tree in component with u
Graph.add_edge(self, u, v)
self.comp[v] = self.comp[u]
else: # make new tree with only u-v
Graph.add_edge(self, u, v)
self.comp[u] = self.nc
self.comp[v] = self.nc
self.nc += 1
def add_edge(self, u, v=None):
if v is None:
(u, v) = u # no v given, assume u is an edge tuple
if self.has_edge(u, v): # no parallel edges
return
elif u in self and v in self:
raise NetworkXError, "adding edge %s-%s not allowed in tree" % (u,
v)
elif u in self:
Graph.add_edge(self, u, v)
self.par[v] = u
return
elif v in self:
Graph.add_edge(self, u, v)
self.par[u] = v
return
elif len(self.adj) == 0: # first leaf
Graph.add_edge(self, u, v)
self.par[v] = u # u is v's parent
return
else:
raise NetworkXError, "adding edge %s-%s not allowed in tree" % (u,
v)
