It's not clear to me what problem you're having. tan(data$slope)
should work. As should log(data$uparea/data$slope) I suggest that you provide a small subset of example data along with an example of any code you've tried, and the output that you'd like. Jean Tom Vanwalleghem wrote on 08/25/2011 05:54:01 AM: > > Dear R helpers, > I'm new to R and struggling with applying functions to a spatial > grid data frame, called data for example.data has a variable named > "slope" and "uparea" > Basically, I need to calculate the tan(data$slope)Next, I need to > divide data$uparea by data$slope and take the log() of that all > In the basic examples I found how to make simple multiplications > with a scalar likedata[["slope"]] = data[["slope"]]/2 # assigns new attribute > I come from a background in GIS and fortran, so used to dealing with > ordinary matrices, I'll admit I'm having trouble with understanding > the format of this spatial grid data frame structureI've been trying > different methods to index the data frame, or working with the > function "lapply" but so far I can't seem to get my head wrapped around it. > I appreciate any help.TomResearcher@University of CordobaSpain > [[alternative HTML version deleted]] > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.