R help - Oct 2007 - Custom colourkey spacing in levelplot, contourplot

Dear R gurus,

I have got stuck on how to customise the colorkey generated by
levelplot and contourplot, in the lattice package. This best
illustrated by an example:

library(lattice)
levelplot(volcano^20/1e45,at=c(0,0.001,0.01,0.1,1,10))

The reason for raising the volcano dataset to the 20th power is to
create a dataset with a large vertical exaggeration - this is similar
in nature to the data set that I am dealing with. Now, if you look at
the colorkey to the right of the plot, you'll see that its basically
dominated by the interval 1:10, and that the 0.001:0.01 color is
virtually invisible, even though it makes up quite a decent fraction
of the actual plot (its the light pink/lavendar colour between the
white and the magenta) .

So the question is, how can I customise the colourkey so that it
consists of five, equally spaced colour intervals, with the
appropriate annotation - in this case I am essentially try to have a
logarithmic distribution of the ticks, but you can imagine that there
will be cases when one wants something completely custom.

Cheers,

Mark

How about


mbreaks <- c(0,0.001,0.01,0.1,1,10)
levelplot(volcano^20/1e45,at=mbreaks,
          colorkey=list(at=1:length(mbreaks),labels = list(labels=mbreaks)))

??


Med venlig hilsen
Frede Aakmann T?gersen
 

 
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> Sendt: 23. oktober 2007 13:28
> Til: r-help at stat.math.ethz.ch
> Emne: [R] Custom colourkey spacing in levelplot, contourplot
> 
> Dear R gurus,
> 
> I have got stuck on how to customise the colorkey generated 
> by levelplot and contourplot, in the lattice package. This 
> best illustrated by an example:
> 
> library(lattice)
> levelplot(volcano^20/1e45,at=c(0,0.001,0.01,0.1,1,10))
> 
> The reason for raising the volcano dataset to the 20th power 
> is to create a dataset with a large vertical exaggeration - 
> this is similar in nature to the data set that I am dealing 
> with. Now, if you look at the colorkey to the right of the 
> plot, you'll see that its basically dominated by the interval 
> 1:10, and that the 0.001:0.01 color is virtually invisible, 
> even though it makes up quite a decent fraction of the actual 
> plot (its the light pink/lavendar colour between the white 
> and the magenta) .
> 
> So the question is, how can I customise the colourkey so that 
> it consists of five, equally spaced colour intervals, with 
> the appropriate annotation - in this case I am essentially 
> try to have a logarithmic distribution of the ticks, but you 
> can imagine that there will be cases when one wants something 
> completely custom.
> 
> Cheers,
> 
> Mark
> 
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