R help - Feb 2010 - contour & persp

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?

Please help, Thanks!

Your frustrated

Andrew

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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