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I have one year of datasets that I want to compute the climatology of 3-day moving averages and then I subtract this climatology from the original values for each pixel.

example:

  # Set up the rasters
r1 <- r2 <- r3 <- r4 <- r5 <- r6 <- raster(nrows=10, ncols=10);
 # Populate them with some values
r1 <- setValues(r1,runif(100,min=1,max=100));
r2 <- setValues(r2,runif(100,min=1,max=100));
r3 <- setValues(r3,runif(100,min=1,max=100));
r4 <- setValues(r4,runif(100,min=1,max=100));
r5 <- setValues(r5,runif(100,min=1,max=100));
r6 <- setValues(r6,runif(100,min=1,max=100));
# Stack them
 st1 <- stack(r1,r2,r3,r4,r5,r6)

Any idea on how to do this.

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x <- calc(st1, function(x) movingFun(x, 3, mean))
y <- st1 - x

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  • Thanks then how to rewrite (r1 ,r2 ,r3 ,r4 , r5 ,r6) from y – usersam Mar 18 '15 at 8:13
  • @usersam r1<-y[[1]] – Pau Mar 18 '15 at 11:57
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try this:

i=1
while (i<(nlayers(st1)-2)) {
 j=i+1
 k=i+2
 #moving averages
 img1= st1[[i]]
 img2= st1[[j]]
 img3=st1[[k]]
 mov_avg=(img1*img2*img3)/3 #or your function
 #write raster: the name of the output will be mov_avg_i.tif, where i= number of iteration (day?)
 writeRaster(mov_avg, paste("c:/mov_avg_",sep=i, ".tif",  format="GTiff", overwrite=TRUE)
 i=i+1
}

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