Spatial packages and Travis

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A number of R spatial libraries have been updated in the last couple of weeks, and this has played havoc with my Travis-CI build. I had still been using Ubuntu Trusty with Travis which uses old versions of libraries like rgdal and rgeos, so I needed to move to updated versions of these. In addition sf has now become a dependency for a number of spatial packages like tmap, and this uses libudunits2-dev which isn’t installed by default.

Spatial microsimulation 101

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I recently gave a presentation for analysts and data modellers at the Department for Work and Pensions (DWP) introducing the spatial microsimulation technique (specifically the IPF flavour), and below are the slides I used (use spacebar to navigate through the slides): Much of the content is based on material from Spatial Microsimulation with R by Robin Lovelace and Morgane Dumont (online content | physical book) and my own rakeR package for R.

Simplify polygons without creating slithers

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When simplifying polygons it’s almost inevitable that you will generate some slither polygons or gaps between the correct polygons. For example, the following image shows two adjoining complex polygons, representing two adjoining administrative areas. Note there are no gaps between the polygons; they are contiguous (the border is between Sheffield and Barnsley LADs, by the way).Original geometries without simplification Now if we simplify these polygons to reduce their complexity using simplify geometries in QGIS, gaps appear between the original two polygons and they are no longer contiguous.

rakeR v0.1.1 released on CRAN

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I’m proud to announce the initial release of rakeR, v0.1.1, has been published on CRAN! It’s licensed under the GPLv3 so you can use it for any projects you wish. Purpose The goal behind rakeR is to make performing spatial microsimulation in R as easy as possible. R is a succinct and expressive language, but previously performing spatial microsimulation required multiple stages, including weighting, integerising, expanding, and subsetting. This doesn’t even include testing inputs and outputs, and validation of the results.

townsendr interactive map

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This week I updated my Townsend Material Deprivation Score project. The update makes townsendr an interactive online map of deprivation that users can simply view in their browser, rather than having to download and run the R code or view only static maps. I think the result is much more intuitive and useful. Making the map interactive is achieved by using Shiny, a technology for R to make interactive charts and plots.

Formal informal testing of research code

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When writing research code I do test my code and results, but until recently I’ve only been doing this informally and not in any systematic way. I decided it was time to change my testing habits when I noticed I had recoded a variable incorrectly despite my informal tests suggesting nothing was wrong. When I went back and corrected this error this made a small, but noticeable, difference to my model.