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/*
* vim: ts=4 sw=4 et tw=0 wm=0
*
* libcola - A library providing force-directed network layout using the
* stress-majorization method subject to separation constraints.
*
* Copyright (C) 2006-2008 Monash University
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library in the file LICENSE; if not,
* write to the Free Software Foundation, Inc., 59 Temple Place,
* Suite 330, Boston, MA 02111-1307 USA
*
*/
// generates a random graph with a power-law distribution of node degrees
// the algorithm is pretty much the Barabasi-Albert model but with an extra step
// so that I can guarantee the number of nodes in the graph.
// We begin with an initial chain of m nodes.
// Then, we add new nodes, connecting them to existing nodes v with probability
// degree(v)/(sum all degrees)
// We perform an extra step, looking for disconnected nodes, connecting them
// to other nodes again with probability dependent on degree
#include<iostream>
#include<vector>
#include <cmath>
#include <time.h>
#include <valarray>
#include "graphlayouttest.h"
void scale_free(const unsigned n = 50) {
const unsigned m = 3; // begin with a chain of m nodes
const double g=0.08; // edge density, every time we add a node we add 1+g*rand(0-1) edges
// connecting them to existing nodes with probability based on degree
unsigned d[n];
double defaultEdgeLength=100;
vector<Edge> es;
CompoundConstraints cx,cy;
for(unsigned i=0;i<n;i++) {
d[i]=0;
}
unsigned sumdegree=0;
for(unsigned i=1;i<m;i++) {
es.push_back(make_pair(i-1,i));
d[i]++;d[i-1]++;
sumdegree+=2;
}
srand(3);
for(unsigned i=2;i<n;i++) {
for(unsigned j=0;j<i;j++) {
double p=(double)d[j]/(double)sumdegree;
double r=(double)rand()/(double)RAND_MAX;
if(r*p>g) {
es.push_back(make_pair(j,i));
d[j]++;d[i]++;
sumdegree+=2;
}
}
}
for(unsigned i=0;i<n;i++) {
if(d[i]==0) {
double maxP=0;
unsigned end=0;
for(unsigned j=0;j<n;j++) {
if(j==i) continue;
double p=(double)d[j]/(double)sumdegree;
double r=(double)rand()/(double)RAND_MAX;
if(r*p>maxP) {
maxP=r*p;
end=j;
}
}
if(end>i) {
es.push_back(make_pair(i,end));
} else {
es.push_back(make_pair(end,i));
}
d[end]++;d[i]++;
sumdegree+=2;
}
}
valarray<double> eweights(es.size());
sort(d,d+n);
unsigned degree=0,ctr=0;
printf("degree distribution:\n");
for(unsigned i=0;i<n;i++) {
if(degree!=d[i]) {
if(degree!=0) printf("%d,%d\n",degree,ctr);
degree=d[i];
ctr=0;
}
ctr++;
}
printf("%d,%d\n",degree,ctr);
for(unsigned i=0;i<es.size();i++) {
unsigned a=es[i].first, b=es[i].second;
eweights[i]=1;
cy.push_back(new SeparationConstraint(a,b,defaultEdgeLength/3));
}
cout << "|V|="<<n<<endl;
double width=1000;
double height=1000;
vector<pair<double,double> > startpos(n);
for(unsigned i=0;i<n;i++) {
double x=getRand(width), y=getRand(height);
startpos[i]=make_pair(x,y);
}
const char *f="scalefree";
//run_test(startpos,es,defaultEdgeLength,cx,cy,CG,false,f,"cg");
//run_test(startpos,es,defaultEdgeLength,cx,cy,IP,false,f,"ip");
//run_test(startpos,es,defaultEdgeLength,cx,cy,UGP,false,f,"ugp");
//run_test(startpos,es,defaultEdgeLength,cx,cy,SGP,false,f,"sgp");
//run_test(startpos,es,defaultEdgeLength,cx,cy,IP,true,f,"cip");
//run_test(startpos,es,defaultEdgeLength,cx,cy,UGP,true,f,"cugp");
run_test(startpos,es,defaultEdgeLength,cx,cy,SGP,true,f,"csgp");
}
int main() {
for(unsigned i=1;i<2;i++) {
scale_free(i*50);
}
return 0;
}
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=4:softtabstop=4:textwidth=99 :
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