def merge_nodes_rhs(self, n1, n2, new_name):
"""Merge3 nodes in rhs."""
if n1 not in self.rhs.nodes():
raise RuleError("Node '%s' is not a node of the rhs" % n1)
if n2 not in self.rhs.nodes():
raise RuleError("Node '%s' is not a node of the rhs" % n2)
primitives.merge_nodes(self.rhs, [n1, n2], node_id=new_name)
for (source, target) in self.p_rhs.items():
if target == n1 or target == n2:
self.p_rhs[source] = new_name
def merge_nodes(self, n1, n2, node_id=None):
"""Merge two nodes of the graph."""
# Update graphs
new_name = None
p_keys_1 = keys_by_value(self.p_lhs, n1)
p_keys_2 = keys_by_value(self.p_lhs, n2)
nodes_to_merge = set()
for k1 in p_keys_1:
if k1 not in self.p.nodes():
raise RuleError(
"Node with the id '%s' does not exist in the "
"preserved part of the rule" % k1
)
for k2 in p_keys_2:
if k2 not in self.p.nodes():
raise RuleError(
"Node with the id '%s' does not exist in "
"the preserved part of the rule" % k2
)
nodes_to_merge.add(self.p_rhs[k1])
nodes_to_merge.add(self.p_rhs[k2])
new_name = primitives.merge_nodes(
self.rhs,
list(nodes_to_merge),
node_id=node_id
)
# Update mappings
keys = p_keys_1 + p_keys_2
for k in keys:
self.p_rhs[k] = new_name
return new_name
def inject_merge_nodes(self, node_list, node_id=None):
"""Inject merge of a collection of nodes by the rule.
Parameters
----------
node_list : iterable
Collection of ids of nodes from the preserved part or
the rhs to merge.
node_id : hashable
Id of the new node corresponding to the result of merge.
Returns
-------
new_name : hashable
Id of the new node corresponding to the result of merge.
Raises
------
RuleError
If a node with some id specified in `node_lust` does not
exist in the preserved part of the rule.
"""
# Update graphs
new_name = None
nodes_to_merge = set()
for n in node_list:
if n in self.p.nodes():
rhs_node = self.p_rhs[n]
elif n in self.rhs.nodes():
rhs_node = n
else:
raise RuleError(
"Node with the id '%s' does not exist in neither the "
"preserved part of the rule nor its rhs" % n
)
nodes_to_merge.add(rhs_node)
new_name = primitives.merge_nodes(
self.rhs,
list(nodes_to_merge),
node_id=node_id
)
# Update mappings
for n in node_list:
if n in self.p.nodes():
self.p_rhs[n] = new_name
for r_node in nodes_to_merge:
merged_ps = keys_by_value(self.p_rhs, r_node)
for p in merged_ps:
self.p_rhs[p] = new_name
return new_name
def pushout_from_relation(g1, g2, relation, inplace=False):
"""Find the pushout from a relation."""
left_dict = left_relation_dict(relation)
right_dict = right_relation_dict(relation)
if inplace is True:
g12 = g1
else:
g12 = copy.deepcopy(g1)
g1_g12 = id_of(g12.nodes())
g2_g12 = dict()
for node in g1.nodes():
if node in left_dict.keys():
for g2_node in left_dict[node]:
g2_g12[g2_node] = node
for node in g2.nodes():
if node not in right_dict.keys():
add_node(g12, node, g2.node[node])
g2_g12[node] = node
elif len(right_dict[node]) == 1:
node_attrs_diff = dict_sub(
g2.node[node],
g1.node[list(right_dict[node])[0]])
add_node_attrs(
g12, list(right_dict[node])[0], node_attrs_diff)
elif len(right_dict[node]) > 1:
new_name = merge_nodes(g12, right_dict[node])
for g1_node in right_dict[node]:
g1_g12[g1_node] = new_name
g2_g12[node] = new_name
node_attrs_diff = dict_sub(
g2.node[node],
g12.node[new_name])
add_node_attrs(g12, new_name, node_attrs_diff)
for u, v in g2.edges():
if (g2_g12[u], g2_g12[v]) not in g12.edges():
add_edge(g12, g2_g12[u], g2_g12[v], get_edge(g2, u, v))
else:
edge_attrs_diff = dict_sub(
g2.edge[u][v],
g12.edge[g2_g12[u]][g2_g12[v]])
add_edge_attrs(g12, g2_g12[u], g2_g12[v], edge_attrs_diff)
return (g12, g1_g12, g2_g12)
def pushout_from_relation(g1, g2, relation, inplace=False):
"""Find the pushout from a relation."""
left_dict = left_relation_dict(relation)
right_dict = right_relation_dict(relation)
if inplace is True:
g12 = g1
else:
g12 = copy.deepcopy(g1)
g1_g12 = id_of(g12.nodes())
g2_g12 = dict()
for node in g1.nodes():
if node in left_dict.keys():
for g2_node in left_dict[node]:
g2_g12[g2_node] = node
for node in g2.nodes():
if node not in right_dict.keys():
add_node(g12, node, g2.node[node])
g2_g12[node] = node
elif len(right_dict[node]) == 1:
node_attrs_diff = dict_sub(g2.node[node],
g1.node[list(right_dict[node])[0]])
add_node_attrs(g12, list(right_dict[node])[0], node_attrs_diff)
elif len(right_dict[node]) > 1:
new_name = merge_nodes(g12, right_dict[node])
for g1_node in right_dict[node]:
g1_g12[g1_node] = new_name
g2_g12[node] = new_name
node_attrs_diff = dict_sub(g2.node[node], g12.node[new_name])
add_node_attrs(g12, new_name, node_attrs_diff)
for u, v in g2.edges():
if (g2_g12[u], g2_g12[v]) not in g12.edges():
add_edge(g12, g2_g12[u], g2_g12[v], get_edge(g2, u, v))
else:
edge_attrs_diff = dict_sub(g2.edge[u][v],
g12.edge[g2_g12[u]][g2_g12[v]])
add_edge_attrs(g12, g2_g12[u], g2_g12[v], edge_attrs_diff)
return (g12, g1_g12, g2_g12)
def pushout(a, b, c, a_b, a_c, inplace=False):
"""Find the pushour of the span b <- a -> c."""
check_homomorphism(a, b, a_b)
check_homomorphism(a, c, a_c)
if inplace is True:
d = b
else:
d = copy.deepcopy(b)
b_d = id_of(b.nodes())
c_d = dict()
# Add/merge nodes
for c_n in c.nodes():
a_keys = keys_by_value(a_c, c_n)
# Add nodes
if len(a_keys) == 0:
add_node(d, c_n, c.node[c_n])
c_d[c_n] = c_n
# Keep nodes
elif len(a_keys) == 1:
c_d[a_c[a_keys[0]]] = a_b[a_keys[0]]
# Merge nodes
else:
nodes_to_merge = []
for k in a_keys:
nodes_to_merge.append(a_b[k])
new_name = merge_nodes(d, nodes_to_merge)
c_d[c_n] = new_name
for node in nodes_to_merge:
b_d[node] = new_name
# Add edges
for (n1, n2) in c.edges():
if b.is_directed():
if (c_d[n1], c_d[n2]) not in d.edges():
add_edge(
d, c_d[n1], c_d[n2],
get_edge(c, n1, n2))
else:
if (c_d[n1], c_d[n2]) not in d.edges() and\
(c_d[n2], c_d[n1]) not in d.edges():
add_edge(
d, c_d[n1], c_d[n2],
get_edge(c, n1, n2)
)
# Add node attrs
for c_n in c.nodes():
a_keys = keys_by_value(a_c, c_n)
# Add attributes to the nodes which stayed invariant
if len(a_keys) == 1:
attrs_to_add = dict_sub(
c.node[c_n],
a.node[a_keys[0]]
)
add_node_attrs(d, c_d[c_n], attrs_to_add)
# Add attributes to the nodes which were merged
elif len(a_keys) > 1:
merged_attrs = {}
for k in a_keys:
merged_attrs = merge_attributes(
merged_attrs,
a.node[k]
)
attrs_to_add = dict_sub(c.node[c_n], merged_attrs)
add_node_attrs(d, c_d[c_n], attrs_to_add)
# Add edge attrs
for (n1, n2) in c.edges():
d_n1 = c_d[n1]
d_n2 = c_d[n2]
if d.is_directed():
attrs_to_add = dict_sub(
get_edge(c, n1, n2),
get_edge(d, d_n1, d_n2)
)
add_edge_attrs(
d, c_d[n1], c_d[n2],
attrs_to_add
)
else:
attrs_to_add = dict_sub(
get_edge(c, n1, n2),
get_edge(d, d_n1, d_n2)
)
add_edge_attrs(
d, c_d[n1], c_d[n2],
attrs_to_add
)
return (d, b_d, c_d)
def pushout(a, b, c, a_b, a_c, inplace=False):
"""Find the pushour of the span b <- a -> c."""
check_homomorphism(a, b, a_b)
check_homomorphism(a, c, a_c)
if inplace is True:
d = b
else:
d = copy.deepcopy(b)
b_d = id_of(b.nodes())
c_d = dict()
# Add/merge nodes
for c_n in c.nodes():
a_keys = keys_by_value(a_c, c_n)
# Add nodes
if len(a_keys) == 0:
add_node(d, c_n, c.node[c_n])
c_d[c_n] = c_n
# Keep nodes
elif len(a_keys) == 1:
c_d[a_c[a_keys[0]]] = a_b[a_keys[0]]
# Merge nodes
else:
nodes_to_merge = []
for k in a_keys:
nodes_to_merge.append(a_b[k])
new_name = merge_nodes(d, nodes_to_merge)
c_d[c_n] = new_name
for node in nodes_to_merge:
b_d[node] = new_name
# Add edges
for (n1, n2) in c.edges():
if b.is_directed():
if (c_d[n1], c_d[n2]) not in d.edges():
add_edge(d, c_d[n1], c_d[n2], get_edge(c, n1, n2))
else:
if (c_d[n1], c_d[n2]) not in d.edges() and\
(c_d[n2], c_d[n1]) not in d.edges():
add_edge(d, c_d[n1], c_d[n2], get_edge(c, n1, n2))
# Add node attrs
for c_n in c.nodes():
a_keys = keys_by_value(a_c, c_n)
# Add attributes to the nodes which stayed invariant
if len(a_keys) == 1:
attrs_to_add = dict_sub(c.node[c_n], a.node[a_keys[0]])
add_node_attrs(d, c_d[c_n], attrs_to_add)
# Add attributes to the nodes which were merged
elif len(a_keys) > 1:
merged_attrs = {}
for k in a_keys:
merged_attrs = merge_attributes(merged_attrs, a.node[k])
attrs_to_add = dict_sub(c.node[c_n], merged_attrs)
add_node_attrs(d, c_d[c_n], attrs_to_add)
# Add edge attrs
for (n1, n2) in c.edges():
d_n1 = c_d[n1]
d_n2 = c_d[n2]
if d.is_directed():
attrs_to_add = dict_sub(get_edge(c, n1, n2),
get_edge(d, d_n1, d_n2))
add_edge_attrs(d, c_d[n1], c_d[n2], attrs_to_add)
else:
attrs_to_add = dict_sub(get_edge(c, n1, n2),
get_edge(d, d_n1, d_n2))
add_edge_attrs(d, c_d[n1], c_d[n2], attrs_to_add)
return (d, b_d, c_d)