graph_preprocessor.cpp

Go to the documentation of this file.

#include <iostream>
#include <string>
#include <utility>
#include <map>
#include <cstdio>
#include <vector>
#include <sys/file.h>
#include <stdint.h>
#include <algorithm>


using namespace std;

template<typename _ForwardIterator>
bool is_sorted(_ForwardIterator __first, _ForwardIterator __last)
{
        if (__first == __last)
                return true;

        _ForwardIterator __next = __first;
        for (++__next; __next != __last; __first = __next, ++__next)
                if (*__next < *__first)
                        return false;
        return true;
}

template<typename _ForwardIter, typename T>
void iota(_ForwardIter __first, _ForwardIter __last, T __value)
{
        while (__first != __last)
                *__first++ = __value++;
}


int main()
{
        int64_t nverts = 133633040;
        int64_t nedges = 5507679822;
        FILE * infp = fopen("uk-union.graph.bin", "rb");
        
        uint32_t * gen_edges = new uint32_t[2*nedges];
        fread(gen_edges, 2*nedges, sizeof(uint32_t), infp);
        cout << "Read data" << endl;    

        vector< vector<uint32_t> > adj(nverts);
        vector< uint32_t > shuffler(nverts);
        iota(shuffler.begin(), shuffler.end(), static_cast<uint32_t>(0));
        random_shuffle ( shuffler.begin(), shuffler.end() );

        for(int64_t i=0; i< 2*nedges; i+=2)
        {
                 adj[shuffler[gen_edges[i]]].push_back(shuffler[gen_edges[i+1]]);
                 adj[shuffler[gen_edges[i+1]]].push_back(shuffler[gen_edges[i]]);
        }
        cout << "Made adjacencies" << endl;
        delete [] gen_edges;
        
        FILE * outp = fopen("uk-union.symmetric.bin", "wb");

        int64_t count = 0;
        for(int64_t i=0; i< nverts; ++i)
        {
                uint32_t edge[2];
                edge[0] = i;
                sort(adj[i].begin(), adj[i].end());
                vector<uint32_t>::iterator p_end = unique(adj[i].begin(), adj[i].end()); // move consecutive duplicates past the end, store the new end
                for(vector<uint32_t>::iterator p = adj[i].begin(); p != p_end; ++p)
                {
                        edge[1] = *p;
                        fwrite(edge, 1, 2*sizeof(uint32_t), outp);
                        ++count;
                }
        }
        fclose(outp);
        cout << "Number of edges: " << count << endl;
}