Hi,
I'm posting again a question that got confused due
to mistakes from my part...
I'd like to clarify a point about internal properties
accessed through a subgraph. According to the
documentation of the method "get(PropertyTag,
subgraph& g)":
"vertex and edge properties are shared by all
subgraphs, so changes to a property through a local
vertex descriptor for one subgraph will change the
property for the global vertex descriptor, and
therefore for all other subgraphs."
(c.f. boost-1.30.2/libs/graph/doc/subgraph.html)
Here, I'm sending you a small program inspired by
the
boost-1.30.2/libs/graph/example/subgraph.cpp example.
From its behavior, it seems that:
1) A property value is not shared between the global
descriptor and its corresponding local descriptors.
2) we need to initialize property values for each of
the subgraphs. For example, if I set a name "A" for
the global vertex descriptor A, that property is not
seen through the corresponding local vertex
descriptors.
Is this a case of misuse or is it a bug?
__________________________________________________________
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/*
Sample output:
After initializing properties for G1:
Global and local properties for vertex G0[C]...
G0[C]= C
G1[A1]= A1
Global and local properties for vertex G0[E]...
G0[E]= E
G1[B1]= B1
Global and local properties for vertex G0[F]...
G0[F]= F
G1[C1]= C1
After initializing properties for G2:
Global and local properties for vertex G0[A]
G0[A]= A
G2[A2]= A2
Global and local properties for vertex G0[C]...
G0[C]= C
G1[A1]= A1
G2[B2]= B2
*/
#include
#include <iostream>
#include
#include
#include
int main(int,char*[])
{
using namespace boost;
//typedef adjacency_list_traits Traits;// Does nothing?
typedef property< vertex_color_t, int,
property< vertex_name_t, std::string > > VertexProperty;
typedef subgraph< adjacency_list< vecS, vecS, directedS,
VertexProperty, property > > Graph;
const int N = 6;
Graph G0(N);
enum { A, B, C, D, E, F}; // for conveniently refering to vertices in G0
property_map::type name = get(vertex_name_t(), G0);
name[A] = "A";
name[B] = "B";
name[C] = "C";
name[D] = "D";
name[E] = "E";
name[F] = "F";
Graph& G1 = G0.create_subgraph();
enum { A1, B1, C1 }; // for conveniently refering to vertices in G1
add_vertex(C, G1); // global vertex C becomes local A1 for G1
add_vertex(E, G1); // global vertex E becomes local B1 for G1
add_vertex(F, G1); // global vertex F becomes local C1 for G1
property_map::type name1 = get(vertex_name_t(), G1);
name1[A1] = "A1";
std::cout << std::endl << "After initializing properties for G1:" << std::endl;
std::cout << " Global and local properties for vertex G0[C]..." << std::endl;
std::cout << " G0[C]= " << boost::get(vertex_name, G0, C) << std::endl;// prints: "G0[C]= C"
std::cout << " G1[A1]= " << boost::get(vertex_name, G1, A1) << std::endl;// prints: "G1[A1]= A1"
name1[B1] = "B1";
std::cout << " Global and local properties for vertex G0[E]..." << std::endl;
std::cout << " G0[E]= " << boost::get(vertex_name, G0, E) << std::endl;// prints: "G0[E]= E"
std::cout << " G1[B1]= " << boost::get(vertex_name, G1, B1) << std::endl;// prints: "G1[B1]= B1"
name1[C1] = "C1";
std::cout << " Global and local properties for vertex G0[F]..." << std::endl;
std::cout << " G0[F]= " << boost::get(vertex_name, G0, F) << std::endl;// prints: "G0[F]= F"
std::cout << " G1[C1]= " << boost::get(vertex_name, G1, C1) << std::endl;// prints: "G1[C1]= C1"
Graph& G2 = G0.create_subgraph();
enum { A2, B2 }; // for conveniently refering to vertices in G2
add_vertex(A, G2); // global vertex A becomes local A2 for G2
add_vertex(C, G2); // global vertex C becomes local B2 for G2
property_map::type name2 = get(vertex_name_t(), G2);
name2[A2] = "A2";
std::cout << std::endl << std::endl << "After initializing properties for G2:" << std::endl;
std::cout << " Global and local properties for vertex G0[A]" << std::endl;
std::cout << " G0[A]= " << boost::get(vertex_name, G0, A) << std::endl;// prints: "G0[A]= A"
std::cout << " G2[A2]= " << boost::get(vertex_name, G2, A2) << std::endl;// prints: "G2[A2]= A2"
name2[B2] = "B2";
std::cout << " Global and local properties for vertex G0[C]..." << std::endl;
std::cout << " G0[C]= " << boost::get(vertex_name, G0, C) << std::endl;// prints: "G0[C]= C"
std::cout << " G1[A1]= " << boost::get(vertex_name, G1, A1) << std::endl;// prints: "G1[A1]= A1"
std::cout << " G2[B2]= " << boost::get(vertex_name, G2, B2) << std::endl;// prints: "G2[B2]= B2"
return 0;
}
