Hello Again... I¹m making a faceted plot of a response on two categorical
variables using ggplot2 and having troubles with the coloring. Here is a
sample that produces the desired plot:
compareCats <- function(data, res, fac1, fac2, colors) {
require(ggplot2)
p <- ggplot(data, aes(fac1, res)) + facet_grid(. ~ fac2)
jit <- position_jitter(width = 0.1)
p <- p + layer(geom = "jitter", position = jit, color = colors)
print(p)
}
test <- data.frame(res = rnorm(100), fac1 = as.factor(rep(c("A", "B"), 50)),
fac2 = as.factor(rep(c("lrg", "lrg", "sm", "sm"), 25)))
compareCats(data = test, res = res, fac1 = fac1, fac2 = fac2, colors =
c("red", "blue"))
Now, if I get away from idealized data where there are the same number of
data points per group (25 in this case), I run into problems. So, if you
do:
rem <- runif(5, 1, 100) # randomly remove a few points here and there
test <- test[-rem,]
compareCats(data = test, res = res, fac1 = fac1, fac2 = fac2, colors =
c("red", "blue"))
R throws an error due to mismatch between the recycling of colors and the
actual number of data points:
Error in `[<-.data.frame`(`*tmp*`, gp, value = list(colour = c("red", :
replacement element 1 has 2 rows, need 47
I'm new to ggplot2, but have been through the book and the web site enough
to know that my problem is "mapping the varible to the aesthetic"; I also
know I can either "map" or "set" the colors.
The question, finally: is there an simple/elegant way to map a list of two
colors corresponding to A and B onto any random sample size of A and B with
faceting? If not, and I must "set" the colors: Do I compute the length of
all possible combos of A, B with lrg, sm, and then create one long vector of
colors for the entire plot? I tried something like this, and was not
successful, but perhaps could be with more work.
All advice appreciated, Bryan (session info below)
*************
Bryan Hanson
Professor of Chemistry & Biochemistry
DePauw University, Greencastle IN USA
> sessionInfo()
R version 2.9.2 (2009-08-24)
i386-apple-darwin8.11.1
locale:
en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] grid datasets tools utils stats graphics grDevices
methods
[9] base
other attached packages:
[1] ggplot2_0.8.3 reshape_0.8.3 proto_0.3-8 mvbutils_2.2.0
[5] ChemoSpec_1.1 lattice_0.17-25 mvoutlier_1.4 plyr_0.1.8
[9] RColorBrewer_1.0-2 chemometrics_0.4 som_0.3-4
robustbase_0.4-5
[13] rpart_3.1-45 pls_2.1-0 pcaPP_1.7 mvtnorm_0.9-7
[17] nnet_7.2-48 mclust_3.2 MASS_7.2-48 lars_0.9-7
[21] e1071_1.5-19 class_7.2-48
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