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Subject: Re: [Boost-users] Default weight map doesn't work for weighted grid graph in A-star search
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2010-07-14 21:42:01

> All of this is true when building against revision 64030 of Boost. 
> graph_traits.hpp:226: error: no type named ‘vertex_property_type’ in ‘class grid’   I noticed that the documentation for the the
> vertex_index_map parameter says that the graph must have an internal vertex_index property.  Could this be the problem?  If I try to
> add the following line to a working build:
> typedef grid::vertex_index grid_vertex_index;
> I get this error:
> g++ -g -I/src/boost-trunk -Wall -Werror -O3   -c -o astar_maze.o astar_maze.cpp
> astar_maze.cpp:62: error: ‘vertex_index’ in class ‘grid’ does not name a type
> What is supposed to work is:
> boost::property_map<grid, boost::vertex_index>::const_type pm
>   = get(boost::vertex_index, grid());
> If that succeeds, it's an algorithm bug most likely.
> First, I can't get grid_graph's argumentless constructor to work.  The following program does not build.

OK -- I was just saying to try that with some object of type "grid",
however you can construct one.

> #include <boost/graph/grid_graph.hpp>
> int main (int argc, char const *argv[]) {
>   boost::grid_graph<2> g = boost::grid_graph<2>();
>   return 0;
> }
> g++ -g -I/src/boost-trunk -Wall -Werror -O3   -c -o grid.o grid.cpp
> grid.cpp: In function ‘int main(int, const char**)’:
> /src/boost-trunk/boost/graph/grid_graph.hpp:232: error: ‘boost::grid_graph<DimensionsT, VertexIndexT, EdgeIndexT>::grid_graph() [with long unsigned int
> Dimensions = 2ul, VertexIndex = size_t, EdgeIndex = size_t]’ is private
> grid.cpp:4: error: within this context
> /src/boost-trunk/boost/graph/grid_graph.hpp: In constructor ‘boost::grid_graph<DimensionsT, VertexIndexT, EdgeIndexT>::grid_graph() [with long unsigned int
> Dimensions = 2ul, VertexIndex = size_t, EdgeIndex = size_t]’:
> grid.cpp:4:   instantiated from here
> /src/boost-trunk/boost/graph/grid_graph.hpp:232: error: uninitialized member ‘boost::grid_graph<2ul, size_t, size_t>::m_dimension_lengths’ with ‘const’ type
> ‘const boost::array<size_t, 2ul>’
> It looks like the grid_graph() constructor at line grid_graph.hpp 232 needs to initialize m_dimension_lengths.  (Tricky because you need to use curly braces
> and assignment.)
> The program does build if you change the line to:
>   boost::grid_graph<2> g();

That declares a function, though, not a real graph.

> But that's an aside.  In my code can use the m_grid grid graph, which has already been created.  If I remove all the vertex index code and the call to
> astar_search from my program, and add the following line to the maze::solve() function:
> boost::property_map<grid, boost::vertex_index_t>::const_type pm = get(boost::vertex_index, m_grid);
> The program builds.  Does that indicate that it's a problem with astar_search then?

I think so. Does a line like that work with the filtered_graph too?

-- Jeremiah Willcock

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