Re: [Boost-users] BGL connected_components ComponentMap

From: Andreas Fabri (andreas.fabri_at_[hidden])
Date: 2007-09-13 13:52:37

Jens Müller wrote:
> Andreas Fabri wrote:
>> Hello,
>>
>> Why does the ComponentMap not get accessed via the property map
>> obtained with   get(vertex_index, g) ?
> 
> What exactly do you mean? The component map is not just used internally 
> (after all, getting connected components is the whole purpose of the 
> algorithm).
> 
> The color map, which is used internally only, is created using 
> vertex_index if not explicitly passed.
> 
>> Many other algorithms do that, e.g. dijksta_shortest_paths.
> 
> Do exactly what?
> 
> Comparing
> http://www.boost.org/libs/graph/doc/connected_components.html
> and
> http://www.boost.org/libs/graph/doc/dijkstra_shortest_paths.html
> I don't see what you mean.
> 
> For Dijkstra, you don't have to pass the distance map and the color map, 
> they are then created using the color map. Just the same as for 
> connected_components().
> 
>> Is this just an inconsistency, or are there technical reasons.
> 
> I don't see the inconsistency.
> 

In fact there were inconsistencies in my expectations, so don't let
get into (wrong) details.

andreas

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