45 lines
1.1 KiB
Matlab
45 lines
1.1 KiB
Matlab
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% Random graph construction routine.
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% Note 1: Default is Erdos-Renyi graph G(n,0.5)
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% Note 2: Generates undirected, simple graphs only
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%
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% INPUTS: N - number of nodes
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% p - probability, 0<=p<=1
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% E - fixed number of edges; if specified, p is irrelevant
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% OUTPUTS: adj - adjacency matrix of generated graph (symmetric), nxn
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%
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% Other routines used: numEdges.m
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% GB: last updated, Oct 20, 2012
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function adj = randomGraph(n,p,E)
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adj=zeros(n); % initialize adjacency matrix
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switch nargin % number of function arguments
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case 1 % just the number of nodes, n
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% 0.5 - default probability of attachment
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for i=1:n
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for j=i+1:n
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if rand<=0.5; adj(i,j)=1; adj(j,i)=1; end
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end
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end
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case 2 % the number of nodes and the probability of attachment, n, p
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for i=1:n
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for j=i+1:n
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if rand<=p; adj(i,j)=1; adj(j,i)=1; end
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end
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end
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case 3 % fixed number of nodes and edges, n, E
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while numEdges(adj) < E
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i=randi(n); j=randi(n); % pick two random nodes
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if i==j || adj(i,j)>0; continue; end % do not allow self-loops or double edges
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adj(i,j)=adj(i,j)+1; adj(j,i)=adj(i,j);
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end
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end
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