Re: [Boost-users] a vector of subgraphs

Subject: Re: [Boost-users] a vector of subgraphs
From: James C. Sutherland (James.Sutherland_at_[hidden])
Date: 2009-04-08 13:19:32

Pointers should still work.  See below.  You cannot (currently) hold  
references in containers.  I think that this is slated to change in  
the new c++ standard, but don't know much about that...

On Apr 8, 2009, at 8:53 AM, fabricio wrote:

> Ok, but it still won't work for me.
>
> Let me rephrase my problem:
>
> I have a certain Graph g and I must create several subgraphs from it.
> In order to create a subgraph I must declare:
>
> typedef subgraph<adjacency_list> Graph;
> Graph g;
>
> and to create the proper subgraphs from g it must be done:
>
> Graph& g1 = g.subgraph();
>
Graph* g1 = g.subgraph();
>
> where the subgraph method returns a Graph&.
>
> The problem is that I must have "n" different subgraphs and I must
> have a way to iterate through them. So ideally I should have:
>
> vector< Graph& > subg;
>
vector< Graph* > subg;
>
>
> subg.resize(n);
> for (i=0;i<n;++i )
>    subg[i] = g.subgraph();
>
> I guess the use of the reference is necessary so when I insert an edge
> on one of the graphs it reflects on every subgraph.
>
> best regards,
> Fabricio
>
> On 8 abr, 00:57, "Damian Coventry" <Damian.Coven..._at_[hidden]>
> wrote:
>> Agree with James, shared_ptr can help here...
>>
>> typedef subgraph<adjacency_list> Graph;
>> typedef shared_ptr<Graph> GraphPtr;
>> typedef vector<GraphPtr> Graphs;
>>
>> Graphs graphs;
>> graphs.push_back(GraphPtr(new Graph));
>>
>> or perhaps
>>
>> Graphs graphs;
>> graphs.resize(2);
>>
>> graphs[1].reset(new Graph);
>> graphs[1]->DoStuff();
>>
>> graphs[0] = GraphPtr(new Graph);
>> graphs[0]->DoStuff();
>>
>> ~Damian();
>>
>>
>>
>>
>>
>>> -----Original Message-----
>>> From: boost-users-boun..._at_[hidden] [mailto:boost-users-
>>> boun..._at_[hidden]] On Behalf Of fabricio
>>> Sent: Wednesday, 8 April 2009 2:54 p.m.
>>> To: boost-us..._at_[hidden]
>>> Subject: Re: [Boost-users] a vector of subgraphs
>>
>>> oh sorry, forgot to mention, after
>>
>>> vector< Graph& > subG;
>>
>>> I should have something like:
>>
>>> subG.resize(2);
>>> subG(0) = G.subgraph();
>>
>>> and subgraph() returns a Graph&
>>
>>> On 7 abr, 21:04, "James C. Sutherland" <James.Sutherl..._at_[hidden]>
>>> wrote:
>>>> On Apr 7, 2009, at 4:59 PM, fabricio wrote:
>>
>>>>> typedef subgraph< adjacency_list > Graph;
>>
>>>>> Graph G;
>>
>>>>> what I want is to create a:
>>
>>>>> vector< Graph& > subG;
>>
>>>>> but the usage of & here is illegal.
>>
>>>> Why not use pointers?
>>>>         vector<Graph*> subG;
>>>> or
>>>>         vector< boost::shared_ptr<Graph> > subG;
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