从txt文件中读取图表后：
t # 0
v 0 5
v 1 9
v 2 8
v 3 7
e 0 1 4
e 1 2 68
e 3 2 18
我正在试图测试两条边是否是邻居。 这是功能：
bool edgesneighbors(Graph g, edge_iter ep1,edge_iter ep2)
{
vertex_t fromep1 = source(*ep1, g);
vertex_t toep1 = target(*ep1, g);
vertex_t fromep2 = source(*ep2, g);
vertex_t toep2 = target(*ep2, g);
cout<<g[fromep1].id<<"--"<<g[toep1].id<<endl;cout<<g[fromep2].id<<"--"<<g[toep2].id<<endl;
if(graphconnexe(g)){return((fromep1==fromep2)||(fromep1==toep2)||(toep1==toep2)||(fromep2==toep1));}
else {return false;}
}
这是我进行测试的程序的一部分。 我想逐两测试所有边缘。
if (!dataG.empty())
{
edge_pair ep;edge_iter e1,e2;
for (ep = edges(dataG[0]); ep.first != ep.second; ++ep.first) //ep edge number
{
e1=ep.first;
e2=ep.second;
}
cout<<"edgesneighbors"<<edgesneighbors(dataG[0],e1,e2)<<endl;
}
但是当我运行它时，我遇到了“核心转储”错误，我认为它来自
e2=ep.second
我该如何解决这个问题？
有关详细信息，请参阅完整源代码：http://pastebin.com/3HrmJppv
我想知道BOOST中是否有任何预定义的函数来处理边/顶点邻接？
答案 0 :(得分：0)
bool edgesneighbors(Graph g, edge_iter ep1, edge_iter ep2)
按值g进行复制。当然，ep1和ep2不是复制的有效迭代器
参考：
bool edgesneighbors(Graph const& g, edge_iter ep1, edge_iter ep2) {
您使用了ep.second，它是结束迭代器。那是无效的。代替：
if (!dataG.empty()) {
edge_pair ep = edges(dataG[0]);
if (size(ep) >= 2) {
Graph::edge_descriptor e1 = ep.first++;
Graph::edge_descriptor e2 = ep.first++;
cout << "edgesneighbors" << edgesneighbors(dataG[0], e1, e2) << endl;
}
}
直到您的分析告诉您此功能存在性能瓶颈：
template <typename Graph, typename E = typename boost::graph_traits<Graph>::edge_descriptor>
bool edgesneighbors(Graph const& g, E e1, E e2) {
std::set<vertex_t> vertex_set {
source(e1, g), target(e1, g),
source(e2, g), target(e2, g),
};
return graphconnexe(g) && vertex_set.size() < 4;
}
所以不需要信任＆＃34;所有这些条件拼写正确。
<强> Live On Coliru
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/vf2_sub_graph_iso.hpp>
#include <boost/algorithm/string/split.hpp>
#include <boost/algorithm/string/classification.hpp>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <ctime>
#include <queue> // std::queue
// for mmap:
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
using namespace std;
using namespace boost;
//==========STRUCTURES==========
// vertex
struct VertexProperties {
int id;
int label;
VertexProperties(unsigned i = 0, unsigned l = 0) : id(i), label(l) {}
};
// edge
struct EdgeProperties {
unsigned id;
unsigned label;
EdgeProperties(unsigned i = 0, unsigned l = 0) : id(i), label(l) {}
};
// Graph
struct GraphProperties {
unsigned id;
unsigned label;
GraphProperties(unsigned i = 0, unsigned l = 0) : id(i), label(l) {}
};
// adjency list
typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, VertexProperties, EdgeProperties,
GraphProperties> Graph;
// descriptors
typedef boost::graph_traits<Graph>::vertex_descriptor vertex_t;
typedef std::pair<boost::graph_traits<Graph>::edge_descriptor, bool> edge_t;
// iterators
typedef graph_traits<Graph>::vertex_iterator vertex_iter;
typedef graph_traits<Graph>::edge_iterator edge_iter;
typedef std::pair<edge_iter, edge_iter> edge_pair;
//==========READ ALL THE FILE AND RETURN A STRING==========
void handle_error(const char *msg) {
perror(msg);
exit(255);
}
//===============================
const char *readfromfile2(const char *fname, size_t &length) {
int fd = open(fname, O_RDONLY);
if (fd == -1)
handle_error("open");
// obtain file size
struct stat sb;
if (fstat(fd, &sb) == -1)
handle_error("fstat");
length = sb.st_size;
const char *addr = static_cast<const char *>(mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0u));
if (addr == MAP_FAILED)
handle_error("mmap");
// TODO close fd at some point in time, call munmap(...)
return addr;
}
//==========SPLIT THE STRING BY NEWLINE (\n) ==========
vector<string> splitstringtolines(string const &str) {
vector<string> split_vector;
split(split_vector, str, is_any_of("\n"));
return split_vector;
}
//==============================================================
string getpos(int pos, string yy) {
size_t i = pos;
string str;
for (; yy[i] != ' ' && i < yy.length(); i++)
str += yy[i];
return str;
}
//==============================================================
std::vector<Graph> creategraphs(std::vector<string> const &fichlines) {
std::vector<Graph> dataG;
int compide = 0; // compteur de id edge
for (string yy : fichlines) {
switch (yy[0]) {
case 't': {
string str2 = getpos(4, yy);
unsigned gid = atoi(str2.c_str());
dataG.emplace_back(GraphProperties(gid, gid));
compide = 0;
} break;
case 'v': {
assert(!dataG.empty()); // assert will terminate the program if its argument turns out to be false
// cout<<yy<<endl;
int vId, vLabel;
string vvv = getpos(2, yy);
vId = atoi(vvv.c_str());
string vvvv = getpos((int)vvv.length() + 3, yy);
// cout<<vvvv<<endl;
vLabel = atoi(vvvv.c_str());
boost::add_vertex(VertexProperties(vId, vLabel), dataG.back());
}
break;
case 'e': { // cout<<yy<<endl;
assert(!dataG.empty()); // assert will terminate the program if its argument turns out to be false
int fromId, toId, eLabel;
string eee = getpos(2, yy);
// cout<<eee<<endl;
fromId = atoi(eee.c_str());
string eee2 = getpos((int)eee.length() + 3, yy);
// cout<<eee2<<endl;
toId = atoi(eee2.c_str());
int c = (int)eee.length() + (int)eee2.length() + 4;
// cout<<c<<endl;
string eee3 = getpos(c, yy);
// cout<<eee3<<endl;
eLabel = atoi(eee3.c_str());
boost::add_edge(fromId, toId, EdgeProperties(compide, eLabel), dataG.back());
compide++;
} break;
}
}
return dataG;
}
//==================================================================================
bool graphconnexe(Graph const &g) { return num_edges(g) >= num_vertices(g) - 1; }
//============================================================================
void printgraph(Graph const &gr) {
typedef std::pair<edge_iter, edge_iter> edge_pair;
std::cout << " contains " << num_vertices(gr) << " vertices, and " << num_edges(gr) << " edges " << std::endl;
if (graphconnexe(gr)) {
// Vertex list
if (num_vertices(gr) != 0) {
std::cout << " Vertex list: " << std::endl;
for (size_t i = 0; i < num_vertices(gr); ++i) // size_t vertice number in the graph
{
std::cout << " v[" << i << "] ID: " << gr[i].id << ", Label: " << gr[i].label << std::endl;
}
}
// Edge list
if (num_edges(gr) != 0) {
std::cout << " Edge list: " << std::endl;
edge_pair ep;
for (ep = edges(gr); ep.first != ep.second; ++ep.first) // ep edge number
{
vertex_t from = source(*ep.first, gr);
vertex_t to = target(*ep.first, gr);
edge_t edg = edge(from, to, gr);
std::cout << " e(" << gr[from].id << "," << gr[to].id << ") ID: " << gr[edg.first].id
<< " , Label: " << gr[edg.first].label << std::endl;
}
}
std::cout << "\n\n" << std::endl;
} else {
cout << "Please check this graph connectivity." << endl;
}
}
//==================================================================================
struct my_callback {
template <typename CorrespondenceMap1To2, typename CorrespondenceMap2To1>
bool operator()(CorrespondenceMap1To2 f, CorrespondenceMap2To1 g) const {
return false;
}
};
//==================================================================================
/*bool graphexistance( std::vector<Graph> const& v, Graph item)
{
return std::find(v.begin(), v.end(), item)!=v.end();
}*/
//=========================================================
bool gUe(Graph &g, edge_iter ep, Graph t) {
vertex_t from = source(*ep, t);
vertex_t to = target(*ep, t);
Graph::edge_descriptor copied_edge = boost::add_edge(from, to, t[*ep], g).first;
g[source(copied_edge, g)] = t[from];
g[target(copied_edge, g)] = t[to];
if (graphconnexe(g) && graphconnexe(t)) {
return vf2_subgraph_iso(g, t, my_callback());
} else {
return false;
}
}
//==========================================
bool verticeexist(Graph &g, int vId, int vlabel) {
int cpt = 0;
if (num_edges(g) != 0) {
for (size_t i = 0; i < num_vertices(g); ++i) // size_t vertice number in the graph
{
if ((g[i].id == vId) && (g[i].label == vlabel)) {
cpt++;
}
}
}
return cpt != 0;
}
//========================================
bool edgeexist(Graph g, int fromid, int toid, unsigned elabel) {
int bn = 0;
if (graphconnexe(g)) {
if (num_edges(g) != 0) {
edge_pair ep;
for (ep = edges(g); ep.first != ep.second; ++ep.first) // ep edge number
{
vertex_t from = source(*ep.first, g);
vertex_t to = target(*ep.first, g);
edge_t edg = edge(from, to, g);
if ((g[from].id == fromid) && (g[to].id == toid) && (g[edg.first].label == elabel)) {
bn++;
}
}
}
}
return (bn != 0);
}
// =========================================
bool vareneighbors(Graph g, int a, int b) {
int bn = 0;
if (graphconnexe(g)) {
if (num_edges(g) != 0) {
edge_pair ep;
for (ep = edges(g); ep.first != ep.second; ++ep.first) // ep edge number
{
vertex_t from = source(*ep.first, g);
vertex_t to = target(*ep.first, g);
if (((g[from].id == a) || (g[to].id == a)) && ((g[from].id == b) || (g[to].id == b))) {
bn++;
}
}
}
}
return (bn != 0);
}
//==========================================
template <typename Graph, typename E = typename boost::graph_traits<Graph>::edge_descriptor>
bool edgesneighbors(Graph const& g, E e1, E e2) {
std::set<vertex_t> vertex_set {
source(e1, g), target(e1, g),
source(e2, g), target(e2, g),
};
return graphconnexe(g) && vertex_set.size() < 4;
}
//==========================================
void emptygraphaddedge(Graph &g, int fromId, int toId, int eLabel) {
if (num_edges(g) == 0) {
boost::add_edge(fromId, toId, EdgeProperties(num_edges(g) + 1, eLabel), g);
}
}
//==========================================
int main() {
clock_t start = std::clock();
size_t length;
std::vector<Graph> dataG = creategraphs(splitstringtolines(readfromfile2("testgUe.txt", length)));
typedef std::pair<edge_iter, edge_iter> edge_pair;
if (!dataG.empty()) {
edge_pair ep = edges(dataG[0]);
if (size(ep) >= 2) {
Graph::edge_descriptor e1 = *ep.first++;
Graph::edge_descriptor e2 = *ep.first++;
cout << "edgesneighbors" << edgesneighbors(dataG[0], e1, e2) << endl;
}
}
// end and time
cout << "FILE Contains " << dataG.size() << " graphs.\nTIME: " << (std::clock() - start) / (double)CLOCKS_PER_SEC
<< "s" << endl; // fin du programme.
}
输出：
edgesneighbors1
FILE Contains 1 graphs.
TIME: 0s