[R] contour & persp

[Uwe Ligges]

On 07.02.2010 22:46, Andrew Wang wrote:
> I  have this data set that both x&  y are ordered vectors of length 600&  700 respectively; z is a 600 by 700 matrix whose entry z[i,j] is either a missing value (indicated by 'NaN') or a real number between 0 and 1.  The contour function
>
> contour(x,y,z)
>
> gives me a blank picture. I guess the reason is that most of z-entries are missing, only less than 1% are non missing.
>
> Question (1)
>
> Is there a way that I could manipulate the data or function to have the non-missing values plotted?
>
> Also, trying function "persp" gives me this error message
>
> persp(x,y,z)
>
> Error in persp.default(x, y, z) : invalid 'z' limits
>
> I look at the manual of "persp". I guess, the error message comes from its internal call
>
> zlim = range(z, na.rm = TRUE)
>
> it appears to me that "persp" can't handle missing value yet its manual states clearly
>
> z: a matrix containing the values to be plotted ('NA's are
>            allowed).  Note that ‘x’ can be used instead of ‘z’
>            for convenience.
>
>
> Question (2)
>
> Can "persp" handle missing values in z? if the answer is a  sounding "yes", how should I do in my case?




Works for me:
persp(1:2, 1:2, matrix(c(1:3, NA), nrow=2))


Hence you really need to specify an example where it does not work.... - 
as the posting guide asks you to do anyway.

Uwe Ligges



> Please help, Thanks!
>
> Your frustrated
>
> Andrew
>
>
>
>
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