[R] ggplot2, building a simple formula interface

[Bryan Hanson]

I¹m trying to build a simple formula interface to work with a function using
ggplot2. The following scheme ³works² up until the plot(p) request, at which
point there are complaints about xlim¹s and a blank graphics window.
Looking at str(p) I do see the limits are NULL, plus layer 1 claims to have
an empty data frame (but df is reproduced correctly).  I'm sure I'm missing
something really obvious; alas my ggplot2 book is at work and it's cold
outside!


simple <- function(formula, data, ...){
mf <- model.frame(formula = formula, data = data)    }

res <- rnorm(100)
f1 <- rep(c("C", "D", "D", "C"), 25)
f2 <- rep(c("A", "B"), 50)
mydata <- data.frame(res, f1, f2)

df <- simple(~ res + f1, mydata)
p <- ggplot(df, aes(f1, res)) + geom_boxplot()
plot(p)

Thanks, Bryan
*************
Bryan Hanson
Acting Chair
Professor of Chemistry & Biochemistry
DePauw University, Greencastle IN USA

> sessionInfo()
R version 2.10.1 (2009-12-14)
x86_64-apple-darwin9.8.0

locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8

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

other attached packages:
 [1] ggplot2_0.8.5      digest_0.4.2       reshape_0.8.3      proto_0.3-8
mvbutils_2.5.0     ChemoSpec_1.43
 [7] R.utils_1.2.4      R.oo_1.6.5         R.methodsS3_1.0.3  rgl_0.87
lattice_0.17-26    mvoutlier_1.4
[13] plyr_0.1.9         RColorBrewer_1.0-2 chemometrics_0.5   som_0.3-4
robustbase_0.5-0-1 rpart_3.1-45
[19] pls_2.1-0          pcaPP_1.7          mvtnorm_0.9-8      nnet_7.3-1
mclust_3.4         MASS_7.3-4
[25] lars_0.9-7         e1071_1.5-22       class_7.3-1