[pgrouting-users] Can pgr_connectedComponents be used to find isolated vertices?

Regina Obe lr at pcorp.us
Wed Aug 2 10:56:25 PDT 2023

I would say yes.  If you have multiple components, then those components are
not reachable from each other.


Note this is only considering an undirected graph.


If you have a directed graph, use pgr_strongComponents instead





From: Pgrouting-users [mailto:pgrouting-users-bounces at lists.osgeo.org] On
Behalf Of glad.pen2421 at fastmail.com
Sent: Wednesday, August 2, 2023 12:40 PM
To: pgrouting-users at lists.osgeo.org
Subject: [pgrouting-users] Can pgr_connectedComponents be used to find
isolated vertices?


Dear fellow pgRouting users,


As per the description of `pgr_connectedComponents`, it runs a breadth-first
search to find sets of vertices "that are all reachable from each other".


Does that mean that if `pgr_connectedComponents` results in more than one
connected component, some vertices are definitely not reachable from each


Can this be a way to guarantee that with more than 1 connected component it
is guaranteed that algorithms like `pgr_dijkstra` will definitely fail on
some pairs of vertices?


Thank you.





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