Homec4science
Diffusion ISFC clustering (master) Browse

ISFCClustering/Matlab_Scripts/2019_03_03_BCT/get_components.m
257e25cb59ccmaster

Last Change
Raw File

get_components.m
View Options

function [comps,comp_sizes] = get_components(adj)
% GET_COMPONENTS Connected components
%
% [comps,comp_sizes] = get_components(adj);
%
% Returns the components of an undirected graph specified by the binary and
% undirected adjacency matrix adj. Components and their constitutent nodes are
% assigned the same index and stored in the vector, comps. The vector, comp_sizes,
% contains the number of nodes beloning to each component.
%
% Inputs: adj, binary and undirected adjacency matrix
%
% Outputs: comps, vector of component assignments for each node
% comp_sizes, vector of component sizes
%
% Note: disconnected nodes will appear as components of size 1
%
% J Goni, University of Navarra and Indiana University, 2009/2011
if size(adj,1)~=size(adj,2)
error('this adjacency matrix is not square');
end
if ~any(adj-triu(adj))
adj = adj | adj';
end
%if main diagonal of adj do not contain all ones, i.e. autoloops
if sum(diag(adj))~=size(adj,1)
%the main diagonal is set to ones
adj = adj|speye(size(adj));
end
%Dulmage-Mendelsohn decomposition
[~,p,~,r] = dmperm(adj);
%p indicates a permutation (along rows and columns)
%r is a vector indicating the component boundaries
% List including the number of nodes of each component. ith entry is r(i+1)-r(i)
comp_sizes = diff(r);
% Number of components found.
num_comps = numel(comp_sizes);
% initialization
comps = zeros(1,size(adj,1));
% first position of each component is set to one
comps(r(1:num_comps)) = ones(1,num_comps);
% cumulative sum produces a label for each component (in a consecutive way)
comps = cumsum(comps);
%re-order component labels according to adj.
comps(p) = comps;
c4science · Help