Function to smooth grids using n x n window moving average (low-pass filter)
On 01/19/2011 05:56 PM, piero campa wrote:
Very quick method Paul, I tried on my own by simple pixel by pixel computing and the result is much slower. Good work. Anyway I was trying to understand how to yield a small modification to your code: having a SpatiaGridDataFrame with NA holes, I noticed that the borderline pixels turn to NA too (and that's because x + NA = NA in R by default), letting theholes grow proportionally to the kernel size (just like the border pixels in a fullgrid data frame). I was trying to do add the ability to ignore NAs (just like it's in the sum method with na.rm = TRUE). I can't find the way however. Thank for any suggestion ! Cheers, Piero
Hi Piero, It can probably be done relatively fast, but I would try and use the functions Robert Hijmans suggested. They are much more generic than my approach and probably just as fast, or even faster. cheers, Paul
Paul Hiemstra, MSc Department of Physical Geography Faculty of Geosciences University of Utrecht Heidelberglaan 2 P.O. Box 80.115 3508 TC Utrecht Phone: +3130 253 5773 http://intamap.geo.uu.nl/~paul http://nl.linkedin.com/pub/paul-hiemstra/20/30b/770 currently @ KNMI paul.hiemstra_AT_knmi.nl