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summarization.graph – Graph

summarization.graph – Graph

This module contains abstract class IGraph represents graphs interface and class Graph (based on IGraph) which implements undirected graph.

Examples

Create simple graph with 4 nodes.

>>> g = Graph()
>>> g.add_node('Felidae')
>>> g.add_node('Lion')
>>> g.add_node('Tiger')
>>> g.add_node('Wolf')
>>> sorted(g.nodes())
['Felidae', 'Lion', 'Tiger', 'Wolf']

Add some edges and check neighbours.

>>> g.add_edge(("Felidae", "Lion"))
>>> g.add_edge(("Felidae", "Tiger"))
>>> g.neighbors("Felidae")
['Lion', 'Tiger']

One node has no neighbours.

>>> g.neighbors("Wolf")
[]
class gensim.summarization.graph.Graph

Bases: gensim.summarization.graph.IGraph

Implementation of an undirected graph, based on IGraph.

DEFAULT_WEIGHT

Weight set by default.

Type:float

Initializes object.

DEFAULT_WEIGHT = 0
add_edge(edge, wt=1)

Adds an edge to the graph connecting two nodes.

Parameters:
  • edge ((hashable, hashable)) – Given edge.
  • wt (float, optional) – Weight of new edge.
Raises:

ValueError – If edge already exists in graph.

add_node(node)

Adds given node to the graph.

Note

While nodes can be of any type, it’s strongly recommended to use only numbers and single-line strings as node identifiers if you intend to use write().

Parameters:node (hashable) – Given node.
Raises:ValueError – If node already exists in graph.
del_edge(edge)

Removes given edges from the graph.

Parameters:edge ((hashable, hashable)) – Given edge.
del_node(node)

Removes given node and its edges from the graph.

Parameters:node (hashable) – Given node.
edge_weight(edge)

Returns weight of given edge.

Parameters:edge ((hashable, hashable)) – Given edge.
Returns:Edge weight.
Return type:float
edges()

Returns all edges of the graph.

Returns:Edges of graph.
Return type:list of (hashable, hashable)
has_edge(edge)

Returns whether an edge exists.

Parameters:edge ((hashable, hashable)) – Given edge.
Returns:True if edge exists, False otherwise.
Return type:bool
has_node(node)

Returns whether the requested node exists.

Parameters:node (hashable) – Given node.
Returns:True if node exists, False otherwise.
Return type:bool
iter_edges()

Returns iterator of all edges of the graph.

Yields:(hashable, hashable) – Edges of graph.
neighbors(node)

Returns all nodes that are directly accessible from given node.

Parameters:node (hashable) – Given node identifier.
Returns:Nodes directly accessible from given node.
Return type:list of hashable
nodes()

Returns all nodes of the graph.

Returns:Nodes of graph.
Return type:list of hashable
class gensim.summarization.graph.IGraph

Bases: object

Represents the interface or contract that the graph for TextRank should implement.

add_edge(edge, wt=1)

Adds an edge to the graph connecting two nodes. An edge, here, is a tuple of two nodes.

Parameters:
  • edge ((hashable, hashable)) – Given edge.
  • wt (float, optional) – Weight of new edge.
add_node(node)

Adds given node to the graph.

Note

While nodes can be of any type, it’s strongly recommended to use only numbers and single-line strings as node identifiers if you intend to use write().

Parameters:node (hashable) – Given node
del_node(node)

Removes node and its edges from the graph.

Parameters:node (hashable) – Node to delete.
edge_weight(edge)

Returns weigth of given edge.

Parameters:edge ((hashable, hashable)) – Given edge.
Returns:Edge weight.
Return type:float
edges()

Returns all edges of graph.

Returns:Edges of graph.
Return type:list of (hashable, hashable)
has_edge(edge)

Returns whether an edge exists.

Parameters:edge ((hashable, hashable)) – Given edge.
Returns:True if edge exists, False otherwise.
Return type:bool
has_node(node)

Returns whether the requested node exists.

Parameters:node (hashable) – Given node identifier.
Returns:True if node exists, False otherwise.
Return type:bool
neighbors(node)

Return all nodes that are directly accessible from given node.

Parameters:node (hashable) – Given node identifier.
Returns:Nodes directly accessible from given node.
Return type:list of hashable
nodes()

Returns all nodes of graph.

Returns:Nodes of graph.
Return type:list of hashable