Re: [Boost-users] [BGL] resize/reserve on graph?

Subject: Re: [Boost-users] [BGL] resize/reserve on graph?
From: Geoff Hilton (geoff.hilton_at_[hidden])
Date: 2011-08-09 20:19:50

> On Tue, Aug 9, 2011 at 6:59 PM, Geoff Hilton wrote:
>
>         On Tue, Aug 9, 2011 at 3:13 PM, Geoff Hilton
>
>             If I know that during the execution of the algorithm the graph size
>             must be grown by X number of vertices in one go, is there a way this
>             can be done to avoid multiple allocations such as when using
>             std::vector's reserve(..) or resize(..) member functions without
>             subverting the BGL's documented interface? Currently I use a for
>             loop which iterates over add_vertex(vertex_property, graph). Can a
>             reserve and/or resize equivalent otherwise please be added somewhere?
>
>             Thank you,
>             Geoff
>
>
>      > On 09/08/2011 6:12 PM, Anil Ramapanicker wrote:
>      > I think you are asking about implicit graph where vertices and edges are
>      > unknown at the begining and they are added during the execution of an
>      > algorithm. You can do it in two ways
>      > a) If you are using internal properties then
>      > add_vertex( vertex_whatever,g) will work
>      > b) If you are using exterior property map then use
>     vector_property_map
>      > since the size is unknown
>      >
>     http://www.boost.org/doc/libs/__1_47_0/libs/property_map/doc/__vector_property_map.html
>      > Anil
>
>     That's exactly what I'm already doing. I'm asking because true, at
>     first I do invariably have to use add_vertex(..), but later on I
>     know exactly how many vertices by which to grow the graph at a time
>     due to the algorithm I'm implementing and I wish to add them in as
>     few memory allocations as possible (preferably one) to the existing
>     graph. Thus, something like std::vector's resize/reserve or an
>     equivalent would be useful.
>
>
>     Thank you,
>     Geoff

 >On 09/08/2011 7:54 PM, Anil Ramapanicker wrote:
 > Okay, I think I got what you are saying.You may have to content with
 > iteratively adding those vertices.

Possibly, which is why I included the last sentence in my original message.