[postgis-users] Trace network from each source node and check that the trace reaches the sea

[Shaozhong SHI]

Hi, Steve,

Your demonstration script does work.

How to deal with the following scenario?

Suppose that we are handling 3D line strings.  We want to trace walking
down the network.  If there be any line string not properly formed (namely,
it does not present a consistent walking down).

How best put a check so that walking down is stopped?  And, we can report
the missed formed line segment?

Regards,

David

On Thu, 30 Dec 2021 at 23:36, Stephen V. Mather <svm at clevelandmetroparks.com>
wrote:

> Hi David,
>
> This is a good example. I have modified this to walk networks before, and
> it's a minimal and understandable example:
>
> http://blog.cleverelephant.ca/2010/07/network-walking-in-postgis.html
>
> There may be some better ways to do this, as the postgres tooling has
> changed quite a bit. The use of a function may be precluded by some modern
> fancy join type. Others can speak better to that than I can these days.
>
> Also, if you don't mind installing one more thing, pgrouting will do
> network traversal much more efficiently than a *WITH RECURSIVE* network
> traversal:
>
> https://pgrouting.org/
>
>
> Cheers,
>
> Best,
>
> Steve
>
>
> On 12/30/21 4:13 PM, Shaozhong SHI wrote:
>
> *WARNING: This email originated outside of Cleveland Metroparks. DO NOT
> CLICK links or attachments unless you recognize the sender and know the
> content is safe.*
> In hydrological network, how to trace network from each source node and
> check whether the trace can reach the sea?
>
> Any examples?
>
> Regards,
>
> David
>
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