how do you interpolate a gaussian grid to a standard 2.5 degreegrid?
Thanks Roger, I shall have a further look at expand.grid() and the fields package and see what I can do! Jenny
Jenny: If you have two matrices, and know the grid values of the x and y sequences,
you can use expand.grid() and some trial and error to make a data frame with longitude, latitude, and value. From there, I think Krig (or Tps) in the fields package will help, with the "Distance=" argument set to rdist.earth. The next release of the gstat package is also going to support Great Circle distances, but the fields package is written by scientists close to your interests, and is already available. You do need to know the latitude spacings, though.
--- Roger Bivand, NHH, Helleveien 30, N-5045 Bergen, Roger.Bivand at nhh.no -----Original Message----- From: r-help-bounces at stat.math.ethz.ch on behalf of Jenny Barnes Sent: Tue 12.12.2006 11:12 To: r-help at stat.math.ethz.ch Subject: [R] how do you interpolate a gaussian grid to a standard 2.5
degreegrid?
Dear R-help community, I have looked on the R search site and archives but cannot find mention of a
way
of interpolating a gaussian distribution of data to a standard 2.5 degree grid. I have two global dataset and I need to correlate - unfortunately one is a 2.5 degree grid dim[longitude=144,latitude=72] and one is gaussian dim[longitude=192,latitude=94]. I would rally appreciate hearing back from any of you who may have wanted to interpolate your data is this way. If there is no ready-made function you know of but you are willing to share your own methods I would also appreciate any pointers. Many thanks for your time, Jenny Barnes ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jennifer Barnes PhD student - long range drought prediction Climate Extremes Department of Space and Climate Physics University College London Holmbury St Mary, Dorking Surrey RH5 6NT Web: http://climate.mssl.ucl.ac.uk
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jennifer Barnes PhD student - long range drought prediction Climate Extremes Department of Space and Climate Physics University College London Holmbury St Mary, Dorking Surrey RH5 6NT 01483 204149 07916 139187 Web: http://climate.mssl.ucl.ac.uk