On Wed, Sep 5, 2012 at 3:27 PM, David Doria <daviddoria@gmail.com> wrote:

I am trying to keep a heap sorted by values in a property map. I tried the code below, but the compiler does not like my arguments to the heap constructor (PriorityQueueType pq(indirectComparison);). According to the documentation (http://www.boost.org/doc/libs/1_51_0/doc/html/boost/heap/binomial_heap.html), there is a constructor:

explicit binomial_heap(value_compare const & = value_compare());

that takes a value_compare, which I was thinking would of type IndirectComparisonType that I provided (I don't really understand the optional template arguments and the base_maker::compare_argument type of things)?

Here is the indirect_cmp doc for reference: http://www.boost.org/doc/libs/1_51_0/boost/pending/indirect_cmp.hpp

#include <boost/heap/binomial_heap.hpp> #include <boost/pending/indirect_cmp.hpp> #include <boost/array.hpp> #include <boost/graph/grid_graph.hpp> #include <iostream>

int main(int, char*[]) { // Construct a graph boost::array<std::size_t, 2> lengths = { { 2,2 } }; typedef boost::grid_graph<2> GraphType; GraphType graph(lengths); typedef boost::graph_traits<GraphType>::vertex_descriptor Vertex; typedef boost::property_map<GraphType, boost::vertex_index_t>::const_type GridIndexMapType; GridIndexMapType gridIndexMap(get(boost::vertex_index, graph));

// Construct a property map typedef boost::vector_property_map<float, GridIndexMapType> PriorityMapType; PriorityMapType priorityMap(gridIndexMap);

// Construct the indirect comparison functor typedef boost::indirect_cmp<PriorityMapType, std::less<float> > IndirectComparisonType; IndirectComparisonType indirectComparison(priorityMap);

// Construct the queue typedef int ValueType; typedef boost::heap::binomial_heap<ValueType, boost::heap::stable<false>, IndirectComparisonType> PriorityQueueType; PriorityQueueType pq(indirectComparison);

return 0; }

Does anyone know how to provide this indirect comparison functor to the queue properly?

Thanks,

David

I found out that you have to wrap the option: typedef boost::heap::binomial_heap<Vertex, boost::heap::stable<false>, boost::heap::compare<IndirectComparisonType> > PriorityQueueType; versus what I was trying before: typedef boost::heap::binomial_heap<Vertex, boost::heap::stable<false>, IndirectComparisonType > PriorityQueueType; Here is an example of how to do use this indirect heap: http://programmingexamples.net/wiki/CPP/Boost/Heap/IndirectCompare David