Hello all-- I'm attempting to produce overlaid histograms with partially transparent columns. Whether this display will end up being useful, I can't say. But I do want to get it right.
I've already got one solution (shown below), but I tried some other
versions and had questions about my results. (Note: I'm using a quartz
device, so transparency shows up correctly. You might need to print to
a pdf device to get transparency, according to the docs I've read)
--8<---------------cut here---------------start------------->8---
## Working version:
data(lexdec, package="languageR")
attach(lexdec)
x <- log(c(BNCw, Frequency))
label <- c(rep("BNCw", length(BNCw)),
rep("CELEX", length(Frequency)))
h <- data.frame(x, label)
g <- ggplot(h, aes(x=x, fill=label))
g +
geom_bar(position="identity") +
scale_fill_manual(values = c(
alpha("red", 0.5),
alpha("blue", 0.5)))
detach(lexdec)
--8<---------------cut here---------------end--------------->8---
Three questions:
1a) Why does the following code not produce transparent bars?
1b) How can I manually specify the elements of the legend for this
version of the plot?
--8<---------------cut here---------------start------------->8---
## Non-working version
data(lexdec, package="languageR")
g <- ggplot(lexdec)
g +
geom_histogram(aes(x=log(BNCw), fill = alpha("red", .5))) +
geom_histogram(aes(x=log(BNCc), fill = alpha("blue", .5)))
--8<---------------cut here---------------end--------------->8---
2) Does anyone have a way to accomplish the same thing in lattice? I
saw the post at
http://www.nabble.com/Overlay-plots-from-different-data-sets-using-the-Lattice-package-tp14824421p14824421.html,
but couldn't figure out how to extend these suggestions to overlaid
transparent histograms.
Thanks in advance for any help,
/au
> sessionInfo()
R version 2.7.0 (2008-04-22)
powerpc-apple-darwin8.10.1
locale:
C
attached base packages:
[1] grid splines stats graphics grDevices utils datasets
[8] methods base
other attached packages:
[1] ggplot2_0.6 colorspace_0.95 RColorBrewer_1.0-2 MASS_7.2-42
[5] proto_0.3-8 reshape_0.8.0 languageR_0.92 coda_0.13-2
[9] lme4_0.999375-15 Matrix_0.999375-10 zipfR_0.6-0 lattice_0.17-8
[13] Design_2.1-1 survival_2.34-1 Hmisc_3.4-3
--
Austin Frank
http://aufrank.net
GPG Public Key (D7398C2F): http://aufrank.net/personal.asc
pgpY8PedpKU6o.pgp
Description: PGP signature
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