Reading GRASS GIS vector attribute tables into R

Linking GRASS GIS and R will give you a very powerful set of geo-spatial analytical tools. The spgrass6 offers a very convenient interface between GRASS GIS and R. You can read more about this package in Bivand, R. 2007. Using the R-GRASS interface. OSGeo Journal 1, 36-38.

Read the whole vector layer
It allows you amongst others to easily import vector data layers from GRASS GIS into R using the function readVECT6(). This will import the whole vector layer. But what if you you only need to import the attribute table? Importing the whole vector layer would give unnecessarily overhead and would take (much) longer to import. Continue reading “Reading GRASS GIS vector attribute tables into R”

Adding geometry columns to attribute table of vector map

What if you have a vector polygon layer and you want to add a column to the attribute table with the size (area) of each individual polygon? Very simple in QGIS, just go to the vector menu: vector | Geometry tools | Export/Add geometry columns, which will give you the following input screen: Continue reading “Adding geometry columns to attribute table of vector map”

Quick multi attribute edit in QGIS

There seem to be a lot of momentum in the development of QGIS and QGIS plug-ins. Existing plug-ins are regularly updated while new plug-ins are released frequently. One recently released plugin is the quick multi attribute edit plugin. It offers one simple, albeit very handy feature; one click editing of multiple features in a vector layer. Continue reading “Quick multi attribute edit in QGIS”

Linking a lookup table to your vector layer

I was looking for a way to link an attribute table of a vector layer to a look up table, with a one to many relation. As discussed here and here, this does not seem to be possible in QGIS. One of the suggestions was to use the “eVis Event Browser”. This plugin allows you to link to external documents. Although a neat plugin, it is not the same as creating an one-to-many link to a lookup table. Continue reading “Linking a lookup table to your vector layer”