Graphs

Abstract graphs in ReGraph.

This module contains abstract classes for graph objects in ReGraph. Such graph objects represent simple graphs with dictionary-like attributes on nodes and edges.

class regraph.graphs.Graph

Abstract class for graph objects in ReGraph.

Methods

add_edge(self, s, t[, attrs])	Add an edge to a graph.
add_edge_attrs(self, s, t, attrs)	Add attributes of an edge in a graph.
add_edges_from(self, edge_list)	Add edges from an edge list.
add_node(self, node_id[, attrs])	Abstract method for adding a node.
add_node_attrs(self, node, attrs)	Add new attributes to a node.
add_nodes_from(self, node_list)	Add nodes from a node list.
clone_node(self, node_id[, name])	Clone node.
copy_node(self, node_id[, copy_id])	Copy node.
edges(self[, data])	Return the list of edges.
exists_edge(self, s, t)	Check if an edge exists.
export(self, filename)	Export graph to JSON file.
filter_edges_by_attributes(self, attr_key, …)	Filter graph edges by attributes.
find_matching(self, pattern[, nodes])	Find matching of a pattern in a graph.
from_json(json_data)	Create a NetworkX graph from a json-like dictionary.
generate_new_node_id(self, basename)	Generate new unique node identifier.
get_edge(self, s, t)	Get edge attributes.
get_edge_attrs(self, s, t)	Get edge attributes.
get_node(self, n)	Get node attributes.
get_node_attrs(self, n)	Get node attributes.
in_edges(self, node_id)	Return the set of in-coming edges.
load(filename)	Load a graph from a JSON file.
merge_nodes(self, nodes[, node_id, method, …])	Merge a list of nodes.
nodes(self[, data])	Return the list of nodes.
number_of_edges(self, u, v)	Return number of directed edges from u to v.
out_edges(self, node_id)	Return the set of out-going edges.
predecessors(self, node_id)	Return the set of predecessors.
print_graph(self)	Pretty-print the graph.
relabel_node(self, node_id, new_id)	Relabel a node in the graph.
relabel_nodes(self, mapping)	Relabel graph nodes inplace given a mapping.
remove_edge(self, source_id, target_id)	Remove edge from the graph.
remove_edge_attrs(self, s, t, attrs)	Remove attrs of an edge specified by attrs.
remove_node(self, node_id)	Remove node.
remove_node_attrs(self, node_id, attrs)	Remove attrs of a node specified by attrs_dict.
rewrite(self, rule[, instance])	Perform SqPO rewiting of the graph with a rule.
set_edge(self, s, t, attrs[, normalize, update])	Set edge attrs.
set_edge_attrs(self, s, t, attrs[, …])	Set edge attrs.
set_node_attrs(self, node_id, attrs[, …])	Set node attrs.
successors(self, node_id)	Return the set of successors.
to_d3_json(self[, attrs, …])	Create a JSON representation of a graph.
to_json(self)	Create a JSON representation of a graph.
update_edge_attrs(self, s, t, attrs[, normalize])	Update attributes of a node.
update_node_attrs(self, node_id, attrs[, …])	Update attributes of a node.

abstract add_edge(self, s, t, attrs=None, **attr)

Add an edge to a graph.

Parameters

shashable

Source node id.

thashable

Target node id.

attrsdict

Edge attributes.

add_edge_attrs(self, s, t, attrs)

Add attributes of an edge in a graph.

Parameters

shashable

Source node id.

thashable

Target node id.

attrsdict

Dictionary with attributes to remove.

Raises

GraphError

If an edge between s and t does not exist.

add_edges_from(self, edge_list)

Add edges from an edge list.

Parameters

edge_listiterable

Iterable containing a collection of edges, optionally, with their attributes

abstract add_node(self, node_id, attrs=None)

Abstract method for adding a node.

Parameters

node_idhashable

Prefix that is prepended to the new unique name.

attrsdict, optional

Node attributes.

add_node_attrs(self, node, attrs)

Add new attributes to a node.

Parameters

nodehashable

Id of a node to add attributes to.

attrsdict

Attributes to add.

Raises

GraphError

If a node node_id does not exist.

add_nodes_from(self, node_list)

Add nodes from a node list.

Parameters

node_listiterable

Iterable containing a collection of nodes, optionally, with their attributes

clone_node(self, node_id, name=None)

Clone node.

Create a new node, a copy of a node with node_id, and reconnect it with all the adjacent nodes of node_id.

Parameters

node_idhashable,

Id of a node to clone.

namehashable, optional

Id for the clone, if is not specified, new id will be generated.

Returns

new_nodehashable

Id of the new node corresponding to the clone

Raises

GraphError

If node wiht node_id does not exists or a node with name (clone’s name) already exists.

copy_node(self, node_id, copy_id=None)

Copy node.

Create a copy of a node in a graph. A new id for the copy is generated by regraph.primitives.unique_node_id.

Parameters

node_idhashable

Node to copy.

Returns

new_name

Id of the copy node.

abstract edges(self, data=False)

Return the list of edges.

exists_edge(self, s, t)

Check if an edge exists.

Parameters

shashable

Source node id.

thashable

Target node id.

export(self, filename)

Export graph to JSON file.

Parameters

filenamestr

Name of the file to save the json serialization of the graph

filter_edges_by_attributes(self, attr_key, attr_cond)

Filter graph edges by attributes.

Removes all the edges of the graph (inplace) that do not satisfy attr_cond.

Parameters

attrs_keyhashable

Attribute key

attrs_condcallable

Condition for an attribute to satisfy: callable that returns True if condition is satisfied, False otherwise.

abstract find_matching(self, pattern, nodes=None)

Find matching of a pattern in a graph.

classmethod from_json(json_data)

Create a NetworkX graph from a json-like dictionary.

Parameters

json_datadict

JSON-like dictionary with graph representation

generate_new_node_id(self, basename)

Generate new unique node identifier.

abstract get_edge(self, s, t)

Get edge attributes.

Parameters

shashable

Source node id.

thashable

Target node id.

get_edge_attrs(self, s, t)

Get edge attributes.

Parameters

graphnetworkx.(Di)Graph

shashable, source node id.

thashable, target node id.

abstract get_node(self, n)

Get node attributes.

Parameters

shashable

Source node id.

thashable,

Target node id.

get_node_attrs(self, n)

Get node attributes.

Parameters

nhashable

Node id.

in_edges(self, node_id)

Return the set of in-coming edges.

classmethod load(filename)

Load a graph from a JSON file.

Create a networkx.(Di)Graph object from a JSON representation stored in a file.

Parameters

filenamestr

Name of the file to load the json serialization of the graph

Returns

Graph object

Raises

ReGraphError

If was not able to load the file

merge_nodes(self, nodes, node_id=None, method='union', edge_method='union')

Merge a list of nodes.

Parameters

nodesiterable

Collection of node id’s to merge.

node_idhashable, optional

Id of a new node corresponding to the result of merge.

methodoptional

Method of node attributes merge: if “union” the resulting node will contain the union of all attributes of the merged nodes, if “intersection”, the resulting node will contain their intersection. Default value is “union”.

edge_methodoptional

Method of edge attributes merge: if “union” the edges that were merged will contain the union of all attributes, if “intersection” – their ntersection. Default value is “union”.

abstract nodes(self, data=False)

Return the list of nodes.

number_of_edges(self, u, v)

Return number of directed edges from u to v.

out_edges(self, node_id)

Return the set of out-going edges.

abstract predecessors(self, node_id)

Return the set of predecessors.

print_graph(self)

Pretty-print the graph.

relabel_node(self, node_id, new_id)

Relabel a node in the graph.

Parameters

node_idhashable

Id of the node to relabel.

new_idhashable

New label of a node.

relabel_nodes(self, mapping)

Relabel graph nodes inplace given a mapping.

Similar to networkx.relabel.relabel_nodes: https://networkx.github.io/documentation/development/_modules/networkx/relabel.html

Parameters

mapping: dict

A dictionary with keys being old node ids and their values being new id’s of the respective nodes.

Raises

ReGraphError

If new id’s do not define a set of distinct node id’s.

abstract remove_edge(self, source_id, target_id)

Remove edge from the graph.

Parameters

shashable

Source node id.

thashable

Target node id.

remove_edge_attrs(self, s, t, attrs)

Remove attrs of an edge specified by attrs.

Parameters

shashable

Source node id.

thashable

Target node id.

attrsdict

Dictionary with attributes to remove.

Raises

GraphError

If an edge between s and t does not exist.

abstract remove_node(self, node_id)

Remove node.

Parameters

node_idhashable

Node to remove.

remove_node_attrs(self, node_id, attrs)

Remove attrs of a node specified by attrs_dict.

Parameters

node_idhashable

Node whose attributes to remove.

attrsdict

Dictionary with attributes to remove.

Raises

GraphError

If a node with the specified id does not exist.

rewrite(self, rule, instance=None)

Perform SqPO rewiting of the graph with a rule.

Parameters

ruleregraph.Rule

SqPO rewriting rule

instancedict, optional

Instance of the input rule. If not specified, the identity map of the rule’s left-hand side is used

set_edge(self, s, t, attrs, normalize=True, update=True)

Set edge attrs.

Parameters

shashable

Source node id.

thashable

Target node id.

attrsdictionary

Dictionary with attributes to set.

Raises

GraphError

If an edge between s and t does not exist.

set_edge_attrs(self, s, t, attrs, normalize=True, update=True)

Set edge attrs.

Parameters

attrsdict

Dictionary with new attributes to set

normalizebool, optional

Flag, when set to True attributes are normalized to be set-valued. True by default

updatebool, optional

Flag, when set to True attributes whose keys are not present in attrs are removed, True by default

Raises

GraphError

If an edge between s and t does not exist.

set_node_attrs(self, node_id, attrs, normalize=True, update=True)

Set node attrs.

Parameters

node_idhashable

Id of the node to update

attrsdict

Dictionary with new attributes to set

normalizebool, optional

Flag, when set to True attributes are normalized to be set-valued. True by default

updatebool, optional

Flag, when set to True attributes whose keys are not present in attrs are removed, True by default

Raises

GraphError

If a node node_id does not exist.

abstract successors(self, node_id)

Return the set of successors.

to_d3_json(self, attrs=True, node_attrs_to_attach=None, edge_attrs_to_attach=None, nodes=None)

Create a JSON representation of a graph.

to_json(self)

Create a JSON representation of a graph.

abstract update_edge_attrs(self, s, t, attrs, normalize=True)

Update attributes of a node.

Parameters

shashable

Source node of the edge to update.

thashable

Target node of the edge to update.

attrsdict

New attributes to assign to the node

abstract update_node_attrs(self, node_id, attrs, normalize=True)

Update attributes of a node.

Parameters

node_idhashable

Node to update.

attrsdict

New attributes to assign to the node