Hi all, Looking for help aggregating some field data subplots to the plot level (data currently in shapefile format). I have clusters of 4 points (4 subplots = 1 plot). I'd like to create a circle around each cluster that is the smallest circle that would encompass all 4 points. Sort of like a convex hull, but a circle (convex hull, in this case, would give me a triangle because of the layout of the subplots). I am familiar with (and use frequently) the typical geo packages in R - with rgdal, sp, raster, and maptools being my most frequent flyers. Is there a function I'm missing in these (or some other) packages that might be able to help me out? In the attribute table, I have a unique ID for each plot/cluster. So for each plot ID (in this case, consisting of 4 subplots), I'd like to build a circle around all of the subplots.
> str(pts) Formal class 'SpatialPointsDataFrame' [package "sp"] with 5 slots ..@ data :'data.frame': 160 obs. of 12 variables: .. ..$ Plot : num [1:160] 1 1 1 1 2 2 2 2 3 3 ... .. ..$ Subplot : num [1:160] 1 2 3 4 1 2 3 4 1 2 ... I should also mention that it's not always 4 points (subplots), and they aren't always covering the same size area on the ground, so buffering by a constant distance isn't the answer. I have subset out 3 plots (so 12 subplots) into a test file here: https://dl.dropboxusercontent.com/u/72421241/test_subplotsToPlots.zip I have R version 3.3.0. I know it's customary to include code for what I've tried, buuuut, that would be a blank canvas at this point. Googling hasn't really been fruitful for this issue, so I thought you folks might have some good ideas! Thanks, Tina [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo