Mike MacFerrin wrote on 01/05/2012 09:28:56 PM:
> I'm using the {lattice} "levelplot" function to make a (more or less)
2-d
> histogram, and for the most part it's working fine with my data.
However, I
> can't get the color key to do what I need. I can give it labels and
custom
> cutoffs, but my cutoff lines (and hence my labels) aren't evenly
> spaced, instead
> they're more-or-less logarithmic, starting at [0,20,50,100...] and
> continuing on
> up to 5 million.
>
> Levelplot scales the ticks/labels linearly on the color key, leaving
most my
> labels scrunched down atop each other at the bottom and only the last
few
> (..."500K","1M","2M","5M") really visible on the rest of the key. Iwant
each
> gap (no matter its numerical range) to occupy one evenly-spaced
> "block" on the
> color key, so they're all readable by the user. I want it to
> display value on a
> logarithmic scale (0,1,10,100,1000,...). The colorkey only seems to
support
> linear scales (0,2,4,6,8,10,...), at least by default, and I don't see
any
> options in the help to change that default.
>
> Does levelplot support this? Or am I destined to draw the colorkey
manually
> (very painfully using polygon calls and user coordinates)? Or are
> there other
> levelplot-like functions that would facilitate this? Any help is
appreciated,
>
> - Mike
Here's one workaround ...
library(lattice)
dat <- expand.grid(x=15*runif(100), y=100*runif(100))
dat$z <- exp(dat$x) + dat$y^2
dat$lz <- log10(dat$z)
levelplot(lz ~ x * y, dat, at=0:7, colorkey=list(labels=paste("10^", 0:7,
sep="")))
Jean
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