Hi There,
Raster package makes this an easy work!! I didn't have to wallow through my
long code. Thank you to all those who contributed.
Regards
Ogbos
On 22 November 2010 18:43, Robert J. Hijmans <r.hijm...@gmail.com> wrote:
> Ogbos,
>
> You can do this:
>
> library(raster)
> xy<-cbind(x, y)
> r <- rasterize(xy, raster(nrow=120, ncol=60), fun=sum)
>
> rb <- rev(rainbow(255,s=1,v=1,start=0,end=7/12,gamma=1,alpha=1))
> image(r, col=rb, ylab = "Longitude", xlab="Latitude" )
>
>
> Or, in your code, instead of this
> z = t(grid3)
>
> this might work:
> z = <- t(grid3[nrow(grid3):1,])
>
> Robert
>
> On Sun, Nov 21, 2010 at 10:51 PM, ogbos okike <ogbos.ok...@gmail.com>
> wrote:
> > Dear all,
> > I tried to use the code below to generate 3 X 3 grid of
> latitude-longitude
> > data. I use image to view the grid. However, latitude and longitude are
> on
> > the wrong axes. Thus, I want to swap the axes. I tried to swap x and y
> in:
> > image(x, ..) that did not help. I also wish to add color code to the
> plot.
> > Thanks for kind help.
> >
> > portion of the data:
> > -3.3851 -65.3236
> > -3.2696 -65.2364
> > -3.2679 -65.2349
> > -17.6404 164.7025
> > -4.8285 148.8214
> > 2.6477 -67.6568
> > -0.2350 -73.4833
> > -16.8655 40.9587
> > 8.1179 -61.6474
> > -0.2755 93.3401
> > -17.1733 119.9011
> > 1.1245 -69.7640
> > -20.0035 -149.3088
> > -3.4200 177.8753
> > 3.0133 -67.5590
> > 15.4684 -21.9331
> > -17.6166 120.2656
> > -17.3888 165.9368
> > -17.6953 164.7335
> > -1.8623 -74.0017
> > -3.3562 -71.1195
> > -11.5775 130.1496
> >
> > code:
> > xy<-matrix(c(x, y), ncol=2)
> >
> > # 3 deg grid for counts
> > grid3 <- matrix(0, nrow=120, ncol=60)
> >
> > # accumulate counts of points in cells
> > for (i in 1:nrow(xy)) {
> > if (xy[i, 1] == 180)
> > ix = nrow(grid3)
> > else
> > ix <- floor((xy[i,1] + 180) / 3) + 1
> >
> > if (xy[i, 2] == 90)
> > iy = ncol(grid3)
> > else
> > iy <- floor((xy[i,2] + 90) / 3) + 1
> >
> > # catch any subscript errors
> > tryCatch(
> > grid3[ix, iy] <- grid3[ix, iy] + 1,
> > error = function(e) cat("Ignoring point out of bounds:", xy[i,], "\n") )
> > }
> > rb<-rev(rainbow(255,s=1,v=1,start=0,end=7/12,gamma=1,alpha=1))
> > image( x = seq(-88.5, 88.5, 3), y = seq(-178.5, 178.5, 3), z = t(grid3),
> > col=rb, ylab = "Longitude", xlab="Latitude" )
> >
> > [[alternative HTML version deleted]]
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo@stat.math.ethz.ch
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
>
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