Hi, [reposted from r-help]
I am trying to use stackApply() to perform averages over subsets of a brick. However, I am struggling with the indices argument, and how it should be interpreted. Here is a simple working example illustrating my problem: r <- raster() r[] <- 1 inp <- brick(r,r,r,r,r,r)*(1:6) res <- stackApply(inp,c(2,2,3,3,1,1),mean) Now if we look at the values of each object: > inp names : layer.1, layer.2, layer.3, layer.4, layer.5, layer.6 min values : 1, 2, 3, 4, 5, 6 max values : 1, 2, 3, 4, 5, 6 > res names : layer.1, layer.2, layer.3 min values : 3.5, 5.5, 1.5 max values : 3.5, 5.5, 1.5 Now, the problem is that the names and order of the layers in "res" don't line up with the indices that I provided. You can do the maths in your head - e.g. the first two layers of "inp" have values of 1 and 2, so their mean should be 1.5 - however, this is ending up as layer 3 in "res". So how should the indices argument be interpreted in this context? Suggestion: A more intuitive format for the "indices" argument in stackApply might be as a factor - this way the order is implict and stackApply ends up working similar to split() or tapply()... Best wishes, Mark [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo