Bill,
Thanks a bunch that works great!
A
On Tue, Oct 6, 2015 at 2:56 PM, William Dunlap <wdun...@tibco.com> wrote:
> Since the model matrix, cbind(1,time) is the same for all your
> response variables,
> you can calculate this on one call to lm, but you have to rearrange the
> response
> values so that each x,y set is in one column. I think the following
> function does it:
>
> f <- function (time, y)
> {
> stopifnot(length(dim(y)) == 3, dim(y)[3] == length(time))
> yMatrix <- matrix(aperm(y, c(3, 1, 2)), dim(y)[3])
> fit <- lm(yMatrix ~ time)
> aperm(array(fitted.values(fit), dim(y)[c(3, 1, 2)]), c(2,
> 3, 1))
> }
>
> E.g.,
> > fitted.values(lm(test1[2,5,]~time))
> 1 2 3 4 5 6 7 8 9 10
> 1 2 3 4 5 6 7 8 9 10
> > f(time, test1)[2,5,]
> [1] 1 2 3 4 5 6 7 8 9 10
>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
>
> On Tue, Oct 6, 2015 at 10:42 AM, Adrienne Wootten <amwoo...@ncsu.edu>
> 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?
> >
> > 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.
>
--
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]]
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