I'd also recommend igraph. Description below describes how I'm using igraph (cut and paste from an earlier private email conversation).
I still use grass for some aspects of topology cleaning (eg messy OSM data), but igraph thereafter. This is how I'm using igraph currently... >> I use igraph directly from postgis via pl/r wrappers. I use it mainly for >> least cost routing instead of pgrouting. Besides igraph being a very fast >> routing engine, it opens up possibilities to embed the inputs or outputs >> within other analytics processes or visualizations. >> >> I've written igraph postgis functions that take >> wkb_geoms and build an igraph directed network object. >> >> Other postgis custom functions then query the network and return >> -Node to node Shortest path >> -Node to multinode shortest paths >> -Mode - inward vs outward directed shortest paths >> - travel distance matrices >> -all of the above using R's parallel computing capabilities >> - anything else which canbe done in igraph or R, and returned to >> Postgresql/postgis. >> >> I then use the results to build polylines, isochrones and cost surfaces on >> the fly using the new KNN lateral query pattern in postgis. >> >> And when you create a Postgis materialized view that calls these igraph >> functions, we can present dynamic QGIS visualizations. So if you drag the >> location of a hospital in QGIS, you see the postgis isochrones or >> accessibility surface immediately update when you hit save. >> >> The other thing to bear in mind is that igraph also comes as a python >> library so you might be able to mash up the line graphs into a QGIS panel - >> and instead of calling igraph in postgis via pl/r, you call it via >> pl/Python. Arguably you don't need postgis if you can access the igraph >> Python lib directly from qgis. > My recommendation would be igraph (http://igraph.org/). > Powerful, Open Source (https://github.com/igraph), well documented, and comes > with Python, and C++ and R interfaces. > I used it in the r.connectivity.network addon for GRASS 6 and was quite happy > with it! > > Cheers > Stefan
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