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louvain.cpp
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louvain.cpp
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/* Implementation 7 of BiLouvain Method dated 20.04.2017
Author: Gautam Khanna and Mohit Baid */
/*Input format : 1. Enter number of vertices and edges
2. Enter the edge list(0-indexed)
3. 1 if you want the code to read the label names from "label.txt", 0 otherwise
*/
#include<bits/stdc++.h>
using namespace std;
//defining a community
struct cluster
{
vector<int> vert;
//list of vertices in the community
int blue,red,self;
//to store the degree of red and blue and self loops of the community
bool single;
};
void bfs(vector<int>& colour,vector< vector<int> >& edge_list,int n)
{
bool visited[n];
int i;
for(i=0;i<n;i++)
{
visited[i]=false;
colour[i]=-1;
}
for(i=0;i<n;i++)
{
if(edge_list[i].size()>0)
break;
}
queue<int> q;
q.push(i);
int v;
while(!q.empty())
{
v=q.front();
q.pop();
if(colour[v]==-1)
colour[v]=0;
visited[v]=true;
for(i=0;i<edge_list[v].size();i++)
{
if(!visited[edge_list[v][i]])
{
q.push(edge_list[v][i]);
colour[edge_list[v][i]]=(colour[v]^1);
}
}
}
}
/* Please note that the code assumes all the vertices in the edge list should lie between 0 and n-1*/
//trying something close to path compression
int getParent(int v,vector<int>& parent)
{
//returns id of the parent cluster
if(parent[v]==v)
return v;
return parent[v]=getParent(parent[v],parent);
}
int main()
{
freopen("edge_list.txt","r",stdin);
//freopen("out.txt","w",stdout);
int n,m,i,j,a,b,fl,w;
cin>>n>>m;
//n- number of vertices in the graph
//m- the number of edges in the graph
map<int, map<int,pair<int,int> > >adj;//unordered_map of unordered_map of pairs to store the adjacency list
//first: red edges from i-j, second: blue edges from i-j
map<int,cluster> track;//unordered_map to store the active clusters
vector<int> parent(n);//vector storing the id which is the supernode of that cluster
string label[n]; //for cluster labels
//cout << "\nn = " << n << endl;
vector<int> colour(n,-1);
vector<int> neigh(n,-1);
// int c=0;//stores the colour entered by user
/*creating and initializing n communities*/
for(i=0;i<n;i++)
{
colour[i]=-1;
cluster cl;
cl.vert.resize(0);
parent[i]=i;// initial parent is the node itself
cl.red=cl.blue=cl.self=0;
cl.vert.push_back(i);
cl.single=true;
track[i]=cl;//storing the community
}
cluster c1,c2;
//taking the edge list as input
vector<vector<int> >edge_list(n);
vector<pair<int,int> >in;
vector<int>weights(m,0);
for(i=0;i<m;i++)
{
cin>>a>>b;//>>w;
edge_list[a].push_back(b);
edge_list[b].push_back(a);
weights[i]=1;
in.push_back(make_pair(a,b));
//cout<<a<<" "<<endl;
}
bfs(colour,edge_list,n);
for(i=0;i<n;i++) cout<<colour[i]<<" "; cout<<endl;
for(i=0;i<m;i++)
{
a=in[i].first;
b=in[i].second;
w=weights[i];
c1=track[a];
c2=track[b];
if(colour[a])
{
adj[a][b].first+=w;
adj[b][a].second+=w;
c1.red+=w;
c2.blue+=w;
}
else
{
adj[a][b].second+=w;
adj[b][a].first+=w;
c2.red+=w;
c1.blue+=w;
}
// cout<<a<<" "<<b<<" "<<c1.red<<" "<<c1.blue<<" "<<c2.red<<" "<<c2.blue<<" "<<adj[a][b].first<<" "<<adj[a][b].second<<endl;
track[a]=c1;
track[b]=c2;
}
double modularity=0;
int pass=1;
// cout<<"Enter 1 to give node labels, else press any other number\n";
// cin>>fl; // 1 To indicate node labels available
fl = 0;
if(fl==1)
{
freopen("label.txt","r",stdin);
for(i=0;i<n;i++)
{
cin>>label[i];
cout << "label: " << label[i] << endl;
}
}
cout<<"Pass 0: "<<modularity<<endl;
vector<double> maxmod(n);
bool flag=true;//flag to indicate a positive value of del Q for each pass
while(true)
{
cerr<<"jijij\n";
flag=false;//set flag as false for each pass
double modu=0;
for(map<int,map<int,pair<int,int> > >::iterator it=adj.begin();it!=adj.end();it++)
{
i=it->first;//index of the cluster we are on
//unordered_map<int,int> done;//indicates the clusters which have been visited for a particular index
maxmod[i]=-1;//maximum modularity initialized with -1
int pos=-1;//position where maximum modularity is obtained
double mod;//modularity for a neighbour
cluster c1=track[i];//present community
neigh[i]=i;
/* Going through all the neighbours of cluster i and finding the modularity value*/
for(map<int,pair<int,int> >::iterator j=adj[i].begin();j!=adj[i].end();j++)
{
int p=getParent(j->first,parent);
//p- parent id of the community
//if neighbour part of the same cluster
if(p==i)
continue;
// cerr<<"Red degree: "<<c1.red<<"\n Blue degree: "<<c1.blue<<"\n";
// cerr<<"Red degree: "<<c2.red<<"\n Blue degree: "<<c2.blue<<"\n";
// cerr<<"Red* Blue= "<<c1.red*c2.blue<<"\n edge sqaure "<<m*m<<"\n";
//if neighbour's community has already been visited
// if(done[p]>0)
// continue;
// done[p]++;//updating the done unordered_map so that this cluster is not repeated again
int deg= adj[i][p].first+adj[i][p].second;
//deg= weight of edge between i and p
cluster c2;
c2=track[p];
//neighbouring community
int pro;
if(c1.single && c2.single)
{
//merge singletons. CASE 1
if(c1.red==0)
{
//vertex is blue
mod= c1.blue*1.0/m;
mod *= c2.red*1.0/m;
mod=(1.0/m)-mod;
}
else
{
//vertex is red
mod= c2.blue*1.0/m;
mod *= c1.red*1.0/m;
mod=(1.0/m)-mod;
}
}
else if(c1.single)
{
//singleton and cluster. CASE 2a
if(c1.blue==0)
{
mod= c2.blue*1.0/m;
mod *= c1.red*1.0/m;
mod= (deg*1.0/m)-mod;
}
else
{
//mod=(deg*1.0/m)-((c2.red*1.0*c1.blue)/(m*m));
mod= c1.blue*1.0/m;
mod *= c2.red*1.0/m;
mod= (deg*1.0/m)-mod;
}
}
else if(c2.single)
{
//singleton and cluster. CASE 2b
if(c2.red==0)
{
mod= c2.blue*1.0/m;
mod *= c1.red*1.0/m;
mod= (deg*1.0/m)-mod;
//mod= (deg*1.0/m)-((c1.red*1.0*c2.blue)/(m*m));
}
else
{
mod= c1.blue*1.0/m;
mod *= c2.red*1.0/m;
mod= (deg*1.0/m)-mod;
//mod=(deg*1.0/m)-((c2.red*1.0*c1.blue)/(m*m));
}
}
else
{
//cluster and cluster. CASE 3
double div1;
mod= c2.blue*1.0/m;
mod *= c1.red*1.0/m;
div1= c1.blue*1.0/m;
div1 *= c2.red*1.0/m;
mod= (deg*1.0/m)-div1-mod;
//mod= (deg*1.0/m)-((c1.red*1.0*c2.blue)/(m*m))-((c2.red*1.0*c1.blue)/(m*m));
}
if(mod>maxmod[i])
{
maxmod[i]=mod;
pos=p;
neigh[i] = p;
}
}
}
// cout<<i<<" "<<pos<<" "<<maxmod<<" "<<endl;
// for(i=0;i<n;i++) cerr<<neigh[i]<<" "<<endl; cout<<endl;
//vector<bool> visited(n,false);
vector<bool> rem(n,false);
modu=0;
for(i=0;i<n;i++)
{
if(adj.find(i) == adj.end()) continue;
int pari = getParent(i,parent);
int parj = getParent(neigh[i],parent);
//if(pari == parj) continue;
if(maxmod[i]>0.000001)
{
int pos=neigh[i];
modu+=maxmod[i];
cluster c1 = track[pari];
cluster c2=track[parj];
//updating cluster 1
c1.single=false;
c1.red+=c2.red-adj[i][pos].first;
c1.blue+=c2.blue-adj[i][pos].second;
c1.self+=c2.self+adj[i][pos].first+adj[i][pos].second;
//cerr<<"merging "<<pari<<" and "<<parj<<endl;
//cerr<<c1.red<<" "<<c1.blue<<" "<<c1.self<<endl;
parent[parj]=i;
for(int kk=0;kk<c2.vert.size();kk++)
{
c1.vert.push_back(c2.vert[kk]);
}
//updating adjacency list: weight of edges from new cluster will include the previous weights ofcluster2
for(map<int,pair<int,int> >:: iterator kk=adj[parj].begin();kk!=adj[parj].end();kk++)
{
adj[pari][kk->first].first+=kk->second.first;
adj[pari][kk->first].second+=kk->second.second;
}
track[pari] = c1;
adj.erase(parj);
track.erase(parj);
}
}
pass++;
if(modularity<modu) modularity=modu;
else break;
cout<<"Pass "<<pass<<": "<<modularity<<endl;
}
cerr<<modularity<<endl;
vector<int> cover(n,0);
/*printing the vertices present in the final clusters after the algo has run, line by line*/
for(map<int,cluster >::iterator it=track.begin();it!=track.end();it++)
{
i=it->first;
cluster c=track[i];
for(j=0;j<c.vert.size();j++)
cover[c.vert[j]]=i;
}
// Make directory
if (system("mkdir clusters") != 0)
{
system("rmdir clusters /s");
system("Y");
system("mkdir clusters");
}
///////////////
freopen("C:\\Users\\HKD\\Lovain\\clusters\\cover.txt","w",stdout);
for(i=0;i<n;i++)
cout<<i<<" "<<cover[i]<<endl;
for(map<int,cluster >::iterator it=track.begin();it!=track.end();it++)
{
if(colour[it->first]!=-1)
{
i=it->first;
stringstream ss;
ss << i;
string filename = "C:\\Users\\HKD\\Lovain\\clusters\\" + ss.str();
filename.append(".txt");
freopen(filename.c_str(),"w",stdout);
cluster c=track[i];
int rctr,bctr;
rctr=bctr=0;
cout<<"Cluster "<<i<<": "<<endl;
cout<<"Vertices in this cluster : "<<c.vert.size()<<endl;
// fl = 1;
for(j=0;j<c.vert.size();j++)
{
if(colour[c.vert[j]]==1)
{
cout<<c.vert[j];
if(fl==1)
cout<<" "<<label[c.vert[j]]<<" -> Red"<<endl;
else
cout<<"-> Red"<<endl;
rctr++;
}
else if(colour[c.vert[j]]==0)
{
cout<<c.vert[j];
if(fl==1)
cout<<" "<<label[c.vert[j]]<<"-> Blue"<<endl;
else
cout<<"-> Blue"<<endl;
bctr++;
}
}
double dens= c.self*1.0;
if(rctr==0 || bctr==0)
dens=0;
else
dens/=(rctr*bctr);
cout<<"Edge density of this cluster = "<<dens<<endl;
cout<<endl<<endl;
}
}
}