Hi Mark, First you need to use cut() to bin the values. Here's an example:
# generate some fake data temp <- data.frame(x=runif(20), y=runif(20), z=runif(20)) # bin x and y temp$x <- cut(temp$x, seq(0, 1, by=.2)) temp$y <- cut(temp$y, seq(0, 1, by=.2)) >From there, there are all sorts of ways to get your desired table. Here are >two: xtabs(z ~ x + y, data=aggregate(z ~ x + y, data=temp, FUN="mean")) or library(ecodist) with(temp, crosstab(x, y, z, "mean")) On Sat, Jul 19, 2014 at 10:57 AM, Mark Miller <mamille...@gmail.com> wrote: > This is probably a basic question, but I haven't been able to Google > anything helpful after trying for days. Using the targeted www.rseek.org search engine is a whole lot more effective than using base Google for R searches. Sarah > I have an R dataframe with x,y,z tuples, where z is a response to x and y > and can be modeled as a surface. > > > head(temp) > x y z > 1 36.55411 965.7779 1644.779 > 2 42.36912 978.9721 1643.957 > 3 58.34699 1183.7426 1846.123 > 4 53.55439 1232.2696 1990.707 > 5 50.76167 1115.2049 1281.988 > 6 51.37299 1059.9088 1597.028 > > I would like to create a matrix of mean z values, with rows representing > binned y values and columns representing binned x values, like > > 0<x<40 40<x<60 60<x<80 x>80 > 0<y<800 1000.0 1100.00 1100.00 1000.0 > 800<y<1200 1000.0 1200.00 1200.00 1000.0 > 1200<y<1400 1000.0 1200.00 1200.00 1000.0 > y<1400 1000.0 1100.00 1100.00 1000.0 > thanks > Mark -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ 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.
