Merging Spatial Data

When working with spatial data, one is rarely interested in working with only one source of data. This tutorial will introduce a set of tools for linking vector data with other data sources. It begins by introducing how to link spatial vector data with non-spatial data in table format, then turns to the problem of linking multiple sources of spatial data through spatial joins and intersects.

This tutorial uses the sp, rgdal, and raster libraries from the RGIS1 tutorial. If you have not yet installed those, please revisit that tutorial for directions. In addition, this tutorial will also make use of the rgeos and plyr libraries, installation of which is discussed in part0_setup.

Most geometric operations – like creating buffers, creating geometric intersections, unions of polygons, etc. – are executed using the rgeos library. Whenever you’re thinking about a geometric operation, rgeos is the first place to look.

1. Installation Instructions

On Windows

1. install.packages(c("rgeos", "plyr")) is usually all you need!

On Macs

Installation of the rgeos library on Macs can be a little tricky – as of September 2015, install.packages("rgeos") will not work on macs (though hopefully this will change soon?). In the meantime, most people find the following directions works:

1. Make sure you have downloaded and installed the GDAL Complete library from RGIS1.
1. Run the following command:

install.packages("rgeos", type = "source", configure.args = "--with-geos-config=/Library/Frameworks/GEOS.framework/Versions/Current/unix/bin/geos-config")

1. Test the installation by typing library(rgeos). If it works, you’re done!
1. If the library fails to load, try the directions on this site
1. Install plyr by install.packages("plyr")

2. Test Installation

To test your installation, just type library(rgeos) and library(plyr). If it loads, you’re set!

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