[R] contour lines on levelplot?

[Spencer Graves]

Thanks very much.  spencer graves

Deepayan Sarkar wrote:

>On Sunday 06 June 2004 20:40, Spencer Graves wrote:
>  
>
>>      With "image" and "contour", one can get both colors and lines
>>to enhance the image of a contour plot.  What's the best way to do
>>this with Lattice graphics?  The following is one ugly hack,
>>producing the desired result after much trial and error (R 1.9.1
>>alpha under Windows 2000):
>>
>># setup
>>DF <- expand.grid(x=1:3, y=1:3)
>>DF$z <- (DF$x+DF$y)
>>
>># Traditional "base" graphics:
>>image(x=1:3, y=1:3, z=array(DF$z, dim=c(3,3)))
>>contour(x=1:3, y=1:3, z=array(DF$z, dim=c(3,3)), add=T)
>>
>># Lattice hack:
>>lvlplt <- levelplot(z~x*y, DF)
>>cont <- contourplot(z~x*y, DF)
>>print(lvlplt, more=T)
>>print(cont, position=c(0, 0, 0.9055, 1))
>>
>>##################
>>      By comparison, the same ugly hack in S-Plus required 0.952
>>instead of 0.955.  Is this the best we can currently get with a
>>modest effort?
>>    
>>
>
>There's certainly much easier ways to do this, namely 
>
>contourplot(z~x*y, DF, region = TRUE)
>
>or 
>
>levelplot(z~x*y, DF, contour = TRUE)
>
>the only restriction being that you would need to use the same 'at' 
>vector. If you want them to differ, you need to write a small panel 
>function of your own that makes use of panel.levelplot().
>
>Deepayan
>  
>