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Package igraph :: Module cut :: Class Cut
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Class Cut

source code

             object --+        
                      |        
  clustering.Clustering --+    
                          |    
clustering.VertexClustering --+
                              |
                             Cut
Known Subclasses:

A cut of a given graph.

This is a simple class used to represent cuts returned by Graph.mincut(), Graph.all_st_cuts() and other functions that calculate cuts.

A cut is a special vertex clustering with only two clusters. Besides the usual VertexClustering methods, it also has the following attributes:

  • value - the value (capacity) of the cut. It is equal to the number of edges if there are no capacities on the edges.
  • partition - vertex IDs in the parts created after removing edges in the cut
  • cut - edge IDs in the cut
  • es - an edge selector restricted to the edges in the cut.

You can use indexing on this object to obtain lists of vertex IDs for both sides of the partition.

This class is usually not instantiated directly, everything is taken care of by the functions that return cuts.

Examples:

>>> from igraph import Graph
>>> g = Graph.Ring(20)
>>> mc = g.mincut()
>>> print mc.value
2.0
>>> print min(map(len, mc))
1
>>> mc.es["color"] = "red"
Instance Methods [hide private]
 
__init__(self, graph, value=None, cut=None, partition=None, partition2=None)
Initializes the cut.
source code
 
__repr__(self)
repr(x)
source code
 
__str__(self)
str(x)
source code

Inherited from clustering.VertexClustering: __plot__, as_cover, cluster_graph, crossing, giant, recalculate_modularity, subgraph, subgraphs

Inherited from clustering.Clustering: __getitem__, __iter__, __len__, compare_to, size, size_histogram, sizes, summary

Inherited from object: __delattr__, __format__, __getattribute__, __hash__, __new__, __reduce__, __reduce_ex__, __setattr__, __sizeof__, __subclasshook__

Class Methods [hide private]

Inherited from clustering.VertexClustering: FromAttribute

Class Variables [hide private]

Inherited from clustering.VertexClustering (private): _default_palette

Properties [hide private]
  es
Returns an edge selector restricted to the cut
  partition
Returns the vertex IDs partitioned according to the cut
  cut
Returns the edge IDs in the cut
  value
Returns the sum of edge capacities in the cut

Inherited from clustering.VertexClustering: graph, modularity, q

Inherited from clustering.Clustering: membership, n

Inherited from object: __class__

Method Details [hide private]

__init__(self, graph, value=None, cut=None, partition=None, partition2=None)
(Constructor)

source code 

Initializes the cut.

This should not be called directly, everything is taken care of by the functions that return cuts.

Parameters:
  • graph - the graph that will be associated to the clustering
  • membership - the membership list. The length of the list must be equal to the number of vertices in the graph. If None, every vertex is assumed to belong to the same cluster.
  • modularity - the modularity score of the clustering. If None, it will be calculated when needed.
  • params - additional parameters to be stored in this object.
  • modularity_params - arguments that should be passed to Graph.modularity when the modularity is (re)calculated. If the original graph was weighted, you should pass a dictionary containing a weight key with the appropriate value here.
Overrides: object.__init__

__repr__(self)
(Representation operator)

source code 

repr(x)

Overrides: object.__repr__
(inherited documentation)

__str__(self)
(Informal representation operator)

source code 

str(x)

Overrides: object.__str__
(inherited documentation)

Property Details [hide private]

es

Returns an edge selector restricted to the cut

Get Method:
unreachable.es(self) - Returns an edge selector restricted to the cut

partition

Returns the vertex IDs partitioned according to the cut

Get Method:
unreachable.partition(self) - Returns the vertex IDs partitioned according to the cut

cut

Returns the edge IDs in the cut

Get Method:
unreachable.cut(self) - Returns the edge IDs in the cut

value

Returns the sum of edge capacities in the cut

Get Method:
unreachable.value(self) - Returns the sum of edge capacities in the cut

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