My latest article, “Network-based functional regions”, has recently been published on-line, with Environment and Planning A. The article can be cited as:
Farmer C J Q, Stewart Fotheringham A, 2011, “Network-based functional regions” Environment and Planning A 43(11) 2723 – 2741
If you would like a copy, but do not have access to the article, please email me and I can forward you a PDF version.
I mentioned a few posts back that there was a great resource for
downloading OpenStreetMap data, and that it was relatively easy to
import osm data into PostgreSQL/PostGIS for use with pgRouting to
calculate shortest paths and various other network-based operations. In
this post, I’ll outline the steps required to get all this up and going,
and provide a quick example to show how this can be combined with QGIS
to visualise the computed shortest path directly.
For part of a traffic simulation project I am currently working on we need country-wide road network data for Ireland. In the past, getting decent road network data for an area this large was quite a task (not to mention expensive and time consuming), however, with OpenStreetMap we have access to this type of data instantly, and for free! In order to download full country coverage all at once, all I had to do was turn to this extremely useful site, which provides links for daily excerpts of OpenStreetMap data for any country in Europe plus several non-country regions such ...
In a recent post, I mentioned that I was testing the stability of clusters generated from a modified network partitioning algorithm using bootstrap resampling techniques. I also mentioned that I was doing this in R, using the very nice foreach package published by REvolution Computing. To show just how nice this package is, below is a minimal example of bootstrapping a network partitioning algorithm which takes advantage of a multicore processor:
In a recent post, I mentioned that I was testing the stability of clusters generated from a modified network partitioning algorithm using bootstrap resampling techniques. I also mentioned that I was doing this in R, using the very nice foreach package published by REvolution Computing. To show just how nice this package is, below is a minimal example of bootstrapping a network partitioning algorithm which takes advantage of a multicore processor:
My PhD research at the moment focuses on network-based algorithms for delineating functional regions (geographical regions within which a large majority of the local population seeks employment, and the majority of local employers recruit their labour). Currently I’m using a network partitioning algorithm based on modularity maximisation. I have found my results to be quite good so far, but, ‘quite good’ isn’t really a very scientific description of validity, so obviously some others means of validation is required. Enter bootstrap resampling!
Many natural and human systems can be represented as networks, including the Internet, social interactions, food webs, and transportation and communication flows. One thing that these types of networks have in common, is that they can each be represented as a series of vertices (or nodes) and edges (or links). This blog entry presents a nice description of networks, highlighting the differences between various network types (directed, undirected, weighted, unweighted, etc.).
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