As has already been noted, there are plenty of GIS questions on SO, particularly in r. Some of these questions clearly belong on SO, in that they are asking for programming advice that just happens to relate to geographical data.
More frequently, however, they are asking if functionality that exists in current GIS systems can be performed in R. The most frequent such topics seem to be:
- Mapping/choropleths (e.g. https://stackoverflow.com/questions/13761265/r-colouring-specific-countries-in-a-spatial-polygon )
- Manipulating shapefiles or KML files (e.g. https://stackoverflow.com/questions/7813141/how-to-create-a-kml-file-using-r )
These I believe clearly belong on GIS.SE, although most still remain on SO.
Yet others fall in a grey area. For instance, this question ( https://stackoverflow.com/questions/10212956/subset-spatialpolygonsdataframe ), wherein common GIS functionality is asked for, but the answer uses base R concepts to implement a custom solution. Similarly, this question about cropping required some custom code and arguably some knowledge of S4 methods, but ultimately the question was one about fundamental GIS capabilities.
I hope with this thread we can come to a consensus on what belongs on SO versus what belongs on GIS.SE .
How much programming is required to make it a programming (and thus SO) question? How much geography is required to make it a GIS.SE question?