[R] Colours on conditional levelplots in package "lattice"

[gordon.morrison at hsbcib.com]

I am having difficulty in getting the colours on a conditional levelplot in
the package lattice to work as I want them to - I wonder if someone could
help me.

The colours do not completely agree with the colour key.

Here is a specimen example.

require(lattice)

col1 <- c
(1.37,2.35,0.20,1.85,0.274,1.56,-0.76,-0.03,-1.39,-0.95,-0.50,0.91,1.58,0.17,-0.34,-0.48,1.50,-0.68,1.05)
col2 <- c
("A","B","C","F","G","H","B","C","E","G","H","A","B","C","D","E","F","G","H")
col3 <- c
("X","Y","X","Y","X","Y","Y","X","X","X","Y","X","Y","X","Y","X","Y","X","Y")
col4 <- c
("1","1","1","1","1","1","2","2","2","2","2","3","3","3","3","3","3","3","3")
dat1 <- data.frame(X1=col1, var1=col2, var2=col3, var3=col4)

maxAbsValue <- max(abs(as.vector(dat1[, "X1"])))
colorkeyAt <- pretty(c(-maxAbsValue, maxAbsValue), n = 10)
boxColours <- c("#8B0000", "#A83500", "#C46B00", "#E2A100", "#FFD700",
"#ADD8E6", "#81A2CF", "#566CB8", "#2B36A1", "#00008B")

levelplot(X1 ~ var1 * var2 | var3, data = dat1,
          col.regions = boxColours,
          colorkey = list(at = colorkeyAt,
              labels = list(labels = colorkeyAt, at = colorkeyAt, cex =
0.6)),
          panel = function(x, y, z, ...) {
            panel.fill(col = "darkgrey")
            at =  pretty(c(-maxAbsValue, maxAbsValue), n = 10)
            panel.levelplot(x, y, z, ...)
          })

I am hoping that all the "blue" shades appear in panel 1, the reds in panel
2 and a mixture only in panel 3. Can anyone help explain why this is not
happening?

I am using

> sessionInfo()
R version 2.11.1 (2010-05-31)
i386-pc-mingw32

locale:
[1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United
Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252

attached base packages:
 [1] grid      grDevices datasets  splines   graphics  stats     tcltk
utils     methods   base

other attached packages:
[1] RColorBrewer_1.0-2 lattice_0.18-8     rcom_2.2-3         rscproxy_1.3-1
svSocket_0.9-48
[6] TinnR_1.0.3        R2HTML_2.1         Hmisc_3.8-2
survival_2.35-8

loaded via a namespace (and not attached):
[1] cluster_1.12.3 svMisc_0.9-57  tools_2.11.1

Windows XP Professional

Regards

Gordon Morrison


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