On Oct 6, 2015, at 10:42 AM, Adrienne Wootten wrote: > R-Helpers, > > I've seen some similar threads about this question online, but not quite > what I'm looking for. I apologize in advance if someone's already answered > this and I just can't find it online. > > Say that I have an array like test3 in the little example code I have below: > > test1 = array(rep(1:10,each = 25),dim=c(5,5,10)) > test2 = array(rnorm(250,0,0.35),dim=c(5,5,10)) > test3 = test1+test2 # array with 5 rows, 5 columns, 10 slices > > time=1:10 > > Where the dimensions are x, y, and time. What I'd like to do is run a > regression (for the sake of this example, say lm) on each x,y in time. So > for a single cell the formula might be test3[1,1,]~time, but I'd like to > that for all cells. The only way I can immediately think of is to use a > loop, but I'm wondering if there's a way to do this without a loop. > Perhaps with tapply?
Would not be expecting a 5x5x10 results since you are using the last dimension to calculate a two parameters for each row and col. Why not use a loop? Doing it with an index is just a a disguised loop: apply( test3, 1:2, function(x) coef(lm(x~time) ) ) # iterates over rows and cols. # results is 5 x 5 x2 > > I'm actually doing a fourth order regression with a much larger array, but > this simple example illustrates the question I have. > > Many thanks for the help! Sorry if someone's already answered this and I > can't find it. > > Adrienne > > -- > Adrienne Wootten > Graduate Research Assistant > State Climate Office of North Carolina > Department of Marine, Earth and Atmospheric Sciences > North Carolina State University > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
