Re: [Boost-users] Default weight map doesn't work for weighted grid graph in A-star search

Subject: Re: [Boost-users] Default weight map doesn't work for weighted grid graph in A-star search
From: W.P. McNeill (billmcn_at_[hidden])
Date: 2010-07-14 21:50:20

On Wed, Jul 14, 2010 at 6:42 PM, Jeremiah Willcock <jewillco_at_[hidden]>wrote:

> 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?
>
> It doesn't work with a filtered_graph.  Adding the following line:

boost::property_map<filtered_grid, boost::vertex_index_t>::const_type fpm =
get(boost::vertex_index, m_barrier_grid);

produces this error:

g++ -g -I/src/boost-trunk -Wall -Werror -O3   -c -o astar_maze.o
astar_maze.cpp
/src/boost-trunk/boost/graph/graph_traits.hpp: In instantiation of
‘boost::vertex_property_type<grid>’:
/src/boost-trunk/boost/graph/filtered_graph.hpp:226:   instantiated from
‘boost::vertex_property_type<filtered_grid>’
/src/boost-trunk/boost/graph/properties.hpp:202:   instantiated from
‘boost::detail::vertex_property_map<filtered_grid, boost::vertex_index_t>’
/src/boost-trunk/boost/graph/properties.hpp:251:   instantiated from
‘boost::property_map<filtered_grid, boost::vertex_index_t>’
astar_maze.cpp:234:   instantiated from here
/src/boost-trunk/boost/graph/graph_traits.hpp:226: error: no type named
‘vertex_property_type’ in ‘class grid’

Which is the same error I was seeing before inside the astar_search call.

> -- Jeremiah Willcock
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