[R] 3D-plots of 2D-grids

[David Winsemius]

On Feb 14, 2013, at 8:05 AM, jas wrote:

> calc_ext3.asc <http://r.789695.n4.nabble.com/file/n4658564/calc_ext3.asc 
> >
>
>
> I supplied a small extent of the grid, that I am trying to  
> visualize. It s a
> ascii-grid with 800 cells. My goal is to display the Grid-Values as  
> the
> z-variable. The point that I dont understand, is what is my input as  
> x and
> y-Variable in the persp-function? Do I have to make 8 vectors with 100
> entries and plot them individually?
>
> Your help is greatly appreciated,
>
> jas
>
> pop.grid
> pop.mat <- as.matrix(pop.grid) # order is not right here already
>
> z <- pop.mat
> x <- 1:nrow(z)
> y <- 1:nrow(z)
> persp(x,y,z, phi=30,  border=NA)
> # Error n persp.default(x, y, z, phi = 30, border = NA) :
>  invalid 'z' Argument

I copied the space separated data from that webpage into my clipboard  
and executed this:

grd <- matrix( scan(), ncol=40, nrow=20)
# and pasted my clipboard
is.na(grd[] ) <- grd == -9999  # use a proper R missing value
  str(grd)
# num [1:20, 1:40] NA NA NA NA NA ...
  persp(z=grd)
  image(grd)

Alternatively you could have used read.table from that file with skip =6

The image looks rather disjointed and I'm hoping that lack of  
continuity is an artifact of extracting only a portion of the data.

-- 
David.

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David Winsemius, MD
Alameda, CA, USA