Re: [Boost-users] vertex descriptors

From: Luis Quesada (luque_at_[hidden])
Date: 2005-12-01 05:27:04

Douglas Gregor wrote:

>On Nov 30, 2005, at 2:06 PM, Luis Quesada wrote:
>  
>
>>Given the index of a vertex, how can I get its descriptor? I guess
>>function vertex (page 225 of The Boost Graph Library) does  that  
>>but the
>>function is not defined.
>>    
>>
>
>For adjacency_list, there is a vertex function:
>
>	vertex(i, g)
>
>returns the ith vertex in the graph g. It's documented in the "Non- 
>Member Functions" section of
>
>	http://www.boost.org/libs/graph/doc/adjacency_list.html
>  
>

Indeed. However vertex returns the descriptor of the ith vertex in the 
*current* graph. What I actually need is the descriptor of the ith 
vertex in the original graph (before any removal has taken place).

If descriptors are not invalidated, the simple solution is to have a 
vector mapping original indexes to descriptors. However, I want to know 
what is the most appropriate way of checking whether edge <i,j> (where i 
and j are original indexes) is in the graph in a context where 
descriptors are invalidated.

Luis