r - Creating multi column legend in ggplot

Question

I have the following script, which suppose to create a plot with two column legend.

 #!/usr/bin/Rscript
library(ggplot2)
library(plyr)
library(reshape2)
library(scales)

file <- "http://dpaste.com/1354089/plain/";
dat <-read.table(file,header=TRUE);
datm <- melt(dat)

# Plot them
ggplot(datm,aes(x = variable,y = value,fill = Term)) +
geom_bar(position = "fill") +
scale_y_continuous(labels = percent_format())+
theme(legend.direction ="vertical",legend.position = "bottom")+

guides(color=guide_legend(ncol=2))+ # this doesn't seem to work

ggsave(file="~/Desktop/test.pdf",width=11,height=11)

But it creates this figure instead

How can I do it correctly?

Answer 1

you must assign the guide to the correct aesthetic and you used fill:

guides(fill=guide_legend(ncol=2))

And you should take care of the warning with geom_bar