a question on lattice contourplots

[epaiv01]

Dear R users,

I am still new to lattice but I am motivated to get to grips with it.
Is it possible to produce the following "traditional R" filled.contour
graph with some equivalent trellis function?

library(lattice);
heights <- c(90, 100, 120, 140, 160, 180, 195);
data(volcano);
filled.contour(volcano, levels=heights, col=terrain.colors(6))

All my attempts to achieve that with the trellis levelplot were futile,
e.g.:
levelplot(volcano, at=heights, col.regions=terrain.colors(6));

The difference actually is in the interpolation: the filled.contour
regions are smooth, while those of levelplot are pixelled.
I tried to see what interpolation filled.contour actually does, but I
could not see the code of filled.contour:
the  actual function is called from the internal R code
(.Internal(filledcontour, ...)), which I do not know how to see.
How could I look into the code of the internal R filledcontour?
I know that levelplot is the lattice equivalent of image, but does
filled.contour also have a lattice eqivalent?

As an alternative, is it possible to fill the regions between the
contour lines in the following plot:
levelplot(volcano, at=heights, col.regions=terrain.colors(6),
contour=TRUE, region=FALSE)
without plotting the contourlines themselves?

Thank You very much for Your attention. Any suggestions will be appreciated.

Best regards,
Martin


--
Dr. Martin Ivanov
Eberhard-Karls-Universität Tübingen
Mathematisch-Naturwissenschaftliche Fakultät
Fachbereich Geowissenschaften
Water & Earth System Science (WESS)
Keplerstraße 17, 72074 Tübingen, Deutschland
Tel. [phone]

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[Tim Appelhans]

Hey Martin,
again me. You can achieve this with the panel.filledcontour() function
that I sent you. You just need to set the fill.cont to TRUE.
If you are looking for a built in lattice equivalent for
filled.contour() I think you are out of luck. Though I suggest ,to be
sure you ask Deepayan Sarkar directly. In the end he's the author of the
lattice package.
Alternatively you could ask Paul Murrell as he's the author of the grid
package. I am sure he will be able to answer your question and give you
all the background on why it may or may not be possible.

Cheers
Tim


On 28/7/2012 13:50, Martin Ivanov wrote:

> Dear R users,
>
> I am still new to lattice but I am motivated to get to grips with it.
> Is it possible to produce the following "traditional R" filled.contour
> graph with some equivalent trellis function?
>
> library(lattice);
> heights <- c(90, 100, 120, 140, 160, 180, 195);
> data(volcano);
> filled.contour(volcano, levels=heights, col=terrain.colors(6))
>
> All my attempts to achieve that with the trellis levelplot were
> futile, e.g.:
> levelplot(volcano, at=heights, col.regions=terrain.colors(6));
>
> The difference actually is in the interpolation: the filled.contour
> regions are smooth, while those of levelplot are pixelled.
> I tried to see what interpolation filled.contour actually does, but I
> could not see the code of filled.contour:
> the  actual function is called from the internal R code
> (.Internal(filledcontour, ...)), which I do not know how to see.
> How could I look into the code of the internal R filledcontour?
> I know that levelplot is the lattice equivalent of image, but does
> filled.contour also have a lattice eqivalent?
>
> As an alternative, is it possible to fill the regions between the
> contour lines in the following plot:
> levelplot(volcano, at=heights, col.regions=terrain.colors(6),
> contour=TRUE, region=FALSE)
> without plotting the contourlines themselves?
>
> Thank You very much for Your attention. Any suggestions will be
> appreciated.
>
> Best regards,
> Martin
>
>

--
#####################################
Tim Appelhans
Department of Geography
Environmental Informatics
Philipps Universität Marburg
Deutschhausstraße 12
35032 Marburg (Paketpost: 35037 Marburg)
Germany

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[Giuseppe Calamita]

Martin Ivanov wrote

....
As an alternative, is it possible to fill the regions between the
contour lines in the following plot:
levelplot(volcano, at=heights, col.regions=terrain.colors(6),
contour=TRUE, region=FALSE)
without plotting the contourlines themselves?
...

well, regarding your last question , you just have to change the parameters of levelplot() function: if you read them, they "speak" clearly ;) : if you don0t want contourlines switch contour parameter to False, and if you want your regions to be coloured switch the region parameter to T
try
levelplot(volcano, at=heights, col.regions=terrain.colors(6), contour=F, region= T)

this should work,