One possibility I can see is to replace -9999 by NA and use mean with na.rm=TRUE.
--- On Wed, 10/2/10, Steve Murray <smurray...@hotmail.com> wrote: > From: Steve Murray <smurray...@hotmail.com> > Subject: [R] Resampling a grid to coarsen its resolution > To: r-help@r-project.org > Received: Wednesday, 10 February, 2010, 3:20 AM > > Dear all, > > I have a grid (data frame) dataset at 0.5 x 0.5 degrees > spatial resolution (720 columns x 360 rows; regular spacing) > and wish to coarsen this to a resolution of 2.5 x 2.5 > degrees. A simple calculation which takes the mean of a > block of points to form the regridded values would do the > trick. Values which should be excluded from the calculation > are -9999 (unless all points within a block are -9999, in > which case -9999 should be returned as the 'new' cell). > > How would I go about achieving this in R? > > Any help or guidelines would be very much appreciated. > > Many thanks, > > Steve > > > > > > > _________________________________________________________________ > Got a cool Hotmail story? Tell us now > > ______________________________________________ > 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. > ______________________________________________ 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.
