[R] Problem using ggplot2 with the legend of a stacked bar chart

John McKown john.archie.mckown at gmail.com
Fri Jul 25 15:07:47 CEST 2014

I am creating two graphs using ggplot2. The graphs are of the same
data. One is a stacked bar chart. The other is a line graph. The code
is below.

MSU_graph_m1   <- ggplot(cpprdald2_m1,aes(x=Int_Start,
#                                          color=System_alias,
                  theme(plot.title = element_text(size = rel(3),
vjust=1, face="bold"),
                        panel.grid.major = element_line(color="black",size=1),
                        panel.grid.minor = element_line(color="black",size=1),
                        legend.text = element_text(size=rel(1.5)),
                        axis.line = element_line(size=3, color="black"),
                        axis.text = element_text(angle=90, size=rel(0.9)),
                        axis.title = element_text(size = rel(2)),
                        axis.ticks = element_line(color="black")) +
                  labs(x="Date and Time",y="MSUs",title=title)+

                  scale_x_datetime(breaks = date_breaks('1 day'),
minor_breaks=date_breaks('1 hour'),  labels=date_format("%b %d
%H:%M")) +
                  scale_y_continuous(breaks = seq(0,LicPrLsys4HMSU_max,5L)) +
                  scale_fill_manual(values=c("yellow","blue")) ;
MSU_graph_m1b  <- MSU_graph_m1+geom_bar(size=0.7,stat="identity");
MSU_graph_m1l  <- MSU_graph_m1+geom_line(size=1.5);

Now, if I use the "color=System_alias", the legend shows up where I
want: on the top,  with the horizontal orientation, and labelled
"LPARs". But I want the order reversed. Which I can't see how to do
using this method. So I added the "guides=(fill..." line to reverse
the legend. But now the legend is on the right, vertically oriented,
and labelled "System_alias" (the variable name).

I now have eye strain from looking at the vignettes and in the book "R
Graphics Cookbook" and just can't figure out a way to get what I want.

Now, using Rstudio, I examined what is in MSU_graph_m1. And saw a
variable called "labels". This is a list containing more variables.
Once of which is called "colour". That variable has the value of
"System_alias". I found that if I set it to the value of "LPARs", then
the legend has the proper title. But I don't like doing this sort of

There is nothing more pleasant than traveling and meeting new people!
Genghis Khan

Maranatha! <><
John McKown

More information about the R-help mailing list