I am trying to analyze how sets of rasters relate to each other using some statistical techniques. As, I don't have much experience using the spatial statistics tools in ArcGIS I was exporting my rasters as Ascii files, and analyzing them using R (specifically the maptools package, and readAsciiGrid() ). This has been functioning ok (but as the datasets have 90,000 points it is slow to run the analysis), but I don't know if I am recreating in R, existing functionality in ArcGIS.

For example, I want to perform regressions between each of these rasters using a few different transformations (logarithmic, exponential, etc). Can this be done within ArcGIS? A second broader question is if there are standard statistical methods for examining this type of data?

Each raster pair has matching data/no-data values and all parameters are identical, aside from the gridcell value.

3 Answers 3


I would stick to R. If speed is really a problem ( I doubt so 90.000 is not such a big number) you could try finding relationships between a subset of your data. Actually the first thing I would do is make a plot to look for obvious relationships.

Even if arcgis contains tools to compare rasters, R will always give you a lot more statistical tools.


samplenr<-sample(length(map1$band1), 1000)
lm(map2~map1, smallset)

I should actually add that often it is more correct to work with a subset of your data then with your full dataset. In many cases grid cells are not independent from the surrounding data cells, which will result in overly optimistic p values for eg regression fits (you will find more info if you search on declustering).

  • 2
    +1. Neither ArcGIS nor, for that matter, any GIS will ever natively provide capabilities like R or other full-featured statistical packages. It would be foolish for them to try. What we can hope for--and ArcGIS appears to be in the early stages--is for the GIS platform to provide efficient integration with other applications for statistical analysis and visualization.
    – whuber
    Commented Jan 5, 2011 at 14:56
  • It's true - speed is not really an issue. It takes about 10s to load two rasters and a 10-15 seconds per operation thus far. If I keep things in perspective, I've waited just as long in ArcGIS for things to happen! I plan to use sampling more, though which will remove any slight delay.
    – djq
    Commented Jan 5, 2011 at 17:03

Look into the R raster package, it was designed with this specific kind of problem in mind. It tries to keep as little of the raster in memory, and performs a number of basic spatial operations -- via GDAL it can handle native ESRI Grid files, among many other formats. The vignette provides some nice examples of its use.


I just read about an ArcGIS 10 package that is an R plugin. I have not had the chance to explore it fully, but it might be possible to modify this to do what I describe above.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.