Adds Markov Clustering to the graph object.

import numpy as np

import networkx as nx

def mcl(g, expand_factor=2, inflate_factor=2, max_loop=10, mult_factor=1):

    """

    Markov Cluster Algorithm

    Implementation modified from: https://github.com/koteth/python_mcl

    Originally released under the MIT license (https://opensource.org/licenses/MIT)

    Parameters

    ----------

    g : object or ndarray

        NetworkX graph object or adjacency matrix

    inflate_factor : float

                     Parameter to strengthen and weaken flow between nodes.  The larger the value

                     the more granular the resultant clusters are.

    expand_factor : int

                    Parameter to manage flow connection between different regions of the graph.

    mult_factor : int

                  Value to set for self loops.

    max_loop : int

               Number of iterations to perform before terminating (or convergence).

    Returns

    -------

    arr : ndarray

          arr normalized flow matrix computed after convergence or max_loop is exceeded.

    clusters : dict

               of clusters where the key is an arbitrary cluster identifier and

               the value is a list of node identifiers.

    References

    ----------

    [Stijn2000]_

    [Stijn2000a]_

    """

    def _normalize(arr):

        """

        Column normalize an array

        Parameters

        ----------

        arr : ndarray

              array to be normalized

        Returns

        -------

        new_matrix : ndarray

                     normalized array

        """

        column_sums = arr.sum(axis=0)

        new_matrix = arr / column_sums[np.newaxis, :]

        return new_matrix

    def _inflate(arr, inflate_factor):

        return _normalize(np.power(arr, inflate_factor))

    def _expand(arr, expand_factor):

        return np.linalg.matrix_power(arr, expand_factor)

    def _add_diag(arr, mult_factor):

        return arr + mult_factor * np.identity(arr.shape[0])

    def _stop(arr, i):

        if i%5==4:

            m = np.max(arr ** 2 - arr) - np.min(arr ** 2 - arr)

            if m==0:

                return True

        return False

    def _get_clusters(arr):

        clusters = {}

        cid = 0

        for j in arr:

            row_positive = np.nonzero(j)[0].tolist()

            if row_positive and not row_positive in clusters.values():

                clusters[cid] = row_positive

                cid += 1

        return clusters

    # Create a dense adjacency matrix

    if isinstance(g, nx.Graph):

        arr = np.array(nx.adjacency_matrix(g).todense())

    elif isinstance(g, np.ndarray):

        arr = g

    arr = _add_diag(arr, mult_factor)

    arr = _normalize(arr)

    for i in range(max_loop):

        #logging.info("loop", i)

        arr = _inflate(arr, inflate_factor)

        arr = _expand(arr, expand_factor)

        # Check for convergence

        if _stop(arr, i): break

    clusters = _get_clusters(arr)

    return arr, clusters

from functools import singledispatch

import itertools

import os

import dill as pickle

import autocnet.matcher.suppression_funcs as spf

from autocnet.graph.edge import Edge

from autocnet.graph.node import Node

from autocnet.graph import markov_cluster

from autocnet.vis.graph_view import plot_graph

                   The number of nodes in the graph. 

    node_name_map : dict

                    The mapping of image labels (i.e. file base names) to their

                    corresponding node indices.

                    corresponding node indices

    clusters : dict

               of clusters with key as the cluster id and value as a

               list of node indices

    ----------

    """

    edge_attr_dict_factory = Edge

        """

        return self.node[node_index].image_name

    def get_node(self, node_name):

        """

        Get the node with the given name.

        Parameters

        ----------

        node_name : str

                    The name of the node.

        Returns

        -------

         : object

           The node with the given image name.

        """

        return self.node[self.node_name_map[node_name]]

    def get_keypoints(self, nodekey):

        """

        Get the list of keypoints for the given node.

        Parameters

        ----------

        nodeIndex : int or string

                    The key for the node, by index or name.

        Returns

        -------

         : list

           The list of keypoints for the given node.

        """

        try:

            return self.get_node(nodekey).keypoints

        except:

            return self.node[nodekey].keypoints

    def add_image(self, *args, **kwargs):

        """

        Adds an image node to the graph.

        """

        raise NotImplementedError

        self.add_node(self.node_counter, *args, **kwargs)

        self.node_counter += 1

    def extract_features(self, method='orb', extractor_parameters={}):

        """

                else:

                    edge.matches = dest_group

    def compute_clusters(self, func=markov_cluster.mcl, *args, **kwargs):

        """

        Apply some graph clustering algorithm to compute a subset of the global

        graph.

        Parameters

        ----------

        func : object

               The clustering function to be applied.  Defaults to

               Markov Clustering Algorithm

        args : list

               of arguments to be passed through to the func

        kwargs : dict

                 of keyword arguments to be passed through to the func

        """

        _, self.clusters = func(self, *args, **kwargs)

    def symmetry_checks(self):

        """

        Perform a symmetry check on all edges in the graph

           A MatPlotLib axes object

        """

        return plot_graph(self, ax=ax,  **kwargs)

    @singledispatch

    def create_subgraph(self, arg, key=None):

        if not hasattr(self, 'clusters'):

            raise AttributeError('No clusters have been computed for this graph.')

        nodes_in_cluster = self.clusters[arg]

        subgraph = self.subgraph(nodes_in_cluster)

        return subgraph

    @create_subgraph.register(pd.DataFrame)

    def _(self, arg, g, key=None):

        if key == None:

            return

        col = arg[key]

        nodes = col[col == True].index

        subgraph = g.subgraph(nodes)

        return subgraph

 No newline at end of file

import unittest

import numpy as np

import networkx as nx

from .. import markov_cluster

from autocnet.examples import get_path

from autocnet.graph.network import CandidateGraph

class TestMarkovCluster(unittest.TestCase):

    def setUp(self):

        self.g = CandidateGraph.from_graph(get_path('sixty_four_apollo.graph'))

    def test_mcl_from_network(self):

        self.g.compute_clusters(inflate_factor=15)

        self.assertIsInstance(self.g.clusters, dict)

        self.assertEqual(len(self.g.clusters), 14)

    def test_mcl_from_adj_matrix(self):

        arr = np.array(nx.adjacency_matrix(self.g).todense())

        flow, clusters = markov_cluster.mcl(arr)

        self.assertIsInstance(clusters, dict)

        self.assertEqual(len(clusters), 3)

        subgraph_list = self.graph.connected_subgraphs()

        self.assertEqual(len(subgraph_list), 1)

    def test_save_load(self):

        self.graph.save('test_save.cg')

        loaded = self.graph.from_graph('test_save.cg')