[pgrouting-users] Disconnected nodes

[Pavel Iacovlev]

Thank you, taking a look
On 16 Apr 2013 18:02, "Stephen Woodbridge" <woodbri at swoodbridge.com> wrote:

> On 4/16/2013 10:49 AM, Pavel Iacovlev wrote:
>
>> Hello,
>>
>> I have a graph and I want to find all the the disconnected nodes, and by
>> "disconnected" I mean all the nodes that have no path to node A. There
>> is a case where A can be more then 1 node, and I need to find out if
>> there is a path to at least one of them.
>>
>> My first idea is just to route to A from each node, easy to implement,
>> but if I will have many nodes this will prove problematic.
>>
>> Any ideas how to do this more efficiently inside PostgreSQL ?
>>
>
> If you check out the sew-devel-2_0 branch in github you will find some
> graph analysis code that does this in src/common/sql/
>
> This can probably just copy the sql and use it. Or at least look at it for
> how it works. Ask if you have questions.
>
> This branch is stable at the moment if you want to clone it and build it
> and give it a test run. It installs on pg 9.1+ as an extension:
>
> create extension pgrouting;
>
> -Steve
>
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