R help - Mar 2012 - sampling matrix 1 conditional on values in matrix 2

Hi
I am trying to estimate bottom temperatures over a particular depth range, based
on one dataset containing synthetic temperature profiles (for set depths) and
another that contains information on bathymetry. I need to do this for multiple
regions and thus would ideally like an automated solution that is quicker and
more accurate than the manual option I currently have! I have not had much luck
and was wondering if someone could help? I understand that this may be a bit of
an ask, but any help/ suggestions is much appreciated.

I see this as a problem involving the sampling of one matrix dependent on the
properties of another measured at a different resolution. Temperature and
bathymetry matrices are geo-referenced, but bathymetry is on a finer spatial
resolution than the temperature data.

Below are some synthetic data in the form that I have access to. I would like to
sample temperatures from locations (from 'syntemp') that have a certain
bottom depth (from 'bath'), e.g. between -200 and -100m.

#bathymetry matrix with 0.1 x 0.1 degree resolution
x<-seq(-250,250,by=1)
x1<-sample(x,441)
bath<-matrix(x1,nrow=21)
bathlong<-seq(149,151,by=.1)
bathlat<-seq(-37,-35,by=.1)
colnames(bath)<-bathlat
rownames(bath)<-bathlong

#temperature matrices with 0.25 x 0.25 degree resolution
##temp at 10m
y<-seq(15,20,by=.01)
y1<-sample(y,81)
temp10<-matrix(y1,nrow=9)
templong<-seq(149,151,by=.25)
templat<-seq(-37,-35,by=.25)
colnames(temp10)<-templat
rownames(temp10)<-templong

##temp at 100m
y<-seq(10,15,by=.01)
y1<-sample(y,81)
temp100<-matrix(y1,nrow=9)
colnames(temp100)<-templat
rownames(temp100)<-templong

##temp at 200m
y<-seq(2,10,by=.01)
y1<-sample(y,81)
temp200<-matrix(y1,nrow=9)
colnames(temp200)<-templat
rownames(temp200)<-templong

###temperature data is available in the form of lists of geo-referenced
temperature profiles (e.g. here are three slices of temp data for region of
interest, normally up to 60 slices for a region at 10m intervals)
syntemp<-list(temp10=temp10,temp100=temp100,temp200=temp200)

Thanks in advance

John




	[[alternative HTML version deleted]]