python-igraph API reference

List of all classes, functions and methods in python-igraph

igraph.cut.Cut

class documentation

class Cut(VertexClustering):

Known subclasses: igraph.cut.Flow

View In Hierarchy

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(len(x) for x in mc))
1
>>> mc.es["color"] = "red"
Method __init__ Initializes the cut.
Method __repr__ Undocumented
Method __str__ Undocumented
Property cut Returns the edge IDs in the cut
Property es Returns an edge selector restricted to the cut
Property partition Returns the vertex IDs partitioned according to the cut
Property value Returns the sum of edge capacities in the cut
Instance Variable _cut Undocumented
Instance Variable _partition Undocumented
Instance Variable _value Undocumented

Inherited from VertexClustering:

Class Method FromAttribute Creates a vertex clustering based on the value of a vertex attribute.
Method __plot__ Plots the clustering to the given Cairo context in the given bounding box.
Method as_cover Returns a VertexCover that contains the same clusters as this clustering.
Method cluster_graph Returns a graph where each cluster is contracted into a single vertex.
Method crossing Returns a boolean vector where element i is True iff edge i lies between clusters, False otherwise.
Method giant Returns the largest cluster of the clustered graph.
Method recalculate_modularity Recalculates the stored modularity value.
Method subgraph Get the subgraph belonging to a given cluster.
Method subgraphs Gets all the subgraphs belonging to each of the clusters.
Property graph Returns the graph belonging to this object
Property modularity Returns the modularity score
Method _formatted_cluster_iterator Iterates over the clusters and formats them into a string to be presented in the summary.
Method _recalculate_modularity_safe Recalculates the stored modularity value and swallows all exceptions raised by the modularity function (if any).
Class Variable _default_palette Undocumented
Instance Variable _graph Undocumented
Instance Variable _modularity Undocumented
Instance Variable _modularity_dirty Undocumented
Instance Variable _modularity_params Undocumented

Inherited from Clustering (via VertexClustering):

Method __getitem__ Returns the members of the specified cluster.
Method __iter__ Iterates over the clusters in this clustering.
Method __len__ Returns the number of clusters.
Method compare_to Compares this clustering to another one using some similarity or distance metric.
Method size Returns the size of a given cluster.
Method size_histogram Returns the histogram of cluster sizes.
Method sizes Returns the size of given clusters.
Method summary Returns the summary of the clustering.
Property membership Returns the membership vector.
Property n Returns the number of elements covered by this clustering.
Instance Variable _len Undocumented
Instance Variable _membership Undocumented
def __init__(self, graph, value=None, cut=None, partition=None, partition2=None):
overrides igraph.clustering.VertexClustering.__init__
overridden in igraph.cut.Flow

Initializes the cut.

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

def __repr__(self):
overridden in igraph.cut.Flow

Undocumented

def __str__(self):
overrides igraph.clustering.Clustering.__str__
overridden in igraph.cut.Flow

Undocumented

@property
cut =

Returns the edge IDs in the cut

@property
es =

Returns an edge selector restricted to the cut

@property
partition =

Returns the vertex IDs partitioned according to the cut

@property
value =

Returns the sum of edge capacities in the cut

_cut =

Undocumented

_partition =

Undocumented

_value =

Undocumented