[R-sig-Geo] Logarithmic legend

[Oscar Perpiñan Lamigueiro]

Hello,

I have been working on a suitable approach with lattice and raster. Now
you can use levelplot with a logarithmic scale both for the colorkey and
the contour lines. 

First you have to install the 0.10-6 version of rasterVis from R-Forge:

install.packages("rasterVis", repos="http://R-Forge.R-project.org")

library(raster)
library(rasterVis) ## 0.10-6

f <- system.file("external/test.grd", package="raster")
r <- raster(f)
levelplot(r, zscaleLog=10, contour=TRUE, labels=TRUE)

Still in development!

Cheers,

Oscar.

-------------------
Oscar Perpiñán Lamigueiro
Dpto. Ingeniería Eléctrica
EUITI-UPM

http://procomun.wordpress.com

-----------------------------------------
>Hi,
>
>You could use ggplot:
>
>library(gstat)
>library(ggplot2)
>loadMeuse()
>
>meuse.grid.df = as.data.frame(meuse.grid)
>head(meuse.grid.df)
>
># Create a dist + 1 for log transformation
># prevents -Inf for 0 values
>meuse.grid.df$dist_plus1 = meuse.grid.df$dist + 1
>
>ggplot(aes(x = x, y = y, fill = dist_plus1), data = meuse.grid.df) +
>geom_tile() +
>    coord_equal() + scale_fill_continuous(trans="log")
>
># Some theme changes I like
>theme_set(theme_bw())
>ggplot(aes(x = x, y = y, fill = dist_plus1), data = meuse.grid.df) +
>geom_tile() +
>    coord_equal() + scale_fill_continuous(trans="log")
>
>hope this helps,
>Paul
>
>On 10/05/2011 06:21 PM, Arnaud Mosnier wrote:
>> Dear Geo Users,
>>
>> Please, can someone explain me how to plot a raster using a
>> logarithmic scale and obtaining the legend with this scale ?
>>
>> Thanks for any help,
>>
>> Arnaud
>>
>> 	[[alternative HTML version deleted]]
>>
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>
>
>-- 
>Paul Hiemstra, Ph.D.
>Global Climate Division
>Royal Netherlands Meteorological Institute (KNMI)
>Wilhelminalaan 10 | 3732 GK | De Bilt | Kamer B 3.39
>P.O. Box 201 | 3730 AE | De Bilt
>tel: +31 30 2206 494
>
>http://intamap.geo.uu.nl/~paul
>http://nl.linkedin.com/pub/paul-hiemstra/20/30b/770