Adjust legend width when colour and linetype are scaled manually

Question

Using this data:

http://pastebin.com/pAQePpxr

And this code:

ggplot(data = trial, aes(x = as.factor(Year), y = DV,group = TMT, col = TMT,linetype=TMT))     +
theme_bw() +
geom_point(size = 3,position = pd) +
geom_errorbar(aes(ymin=trial$DV-trial$Error, ymax=trial$DV+trial$Error),
    position = pd, 
    width = 0.1,
    linetype=1) +
geom_line(position = pd) +
ylab("DV") +
xlab("Year") +
theme(axis.title.y=element_text(size=rel(1.1),vjust=0.2),
    axis.title.x=element_text(size=rel(1.1), vjust=0.2),
    axis.text.x=element_text(size=rel(1)),
    axis.text.y=element_text(size=rel(1)), 
    text = element_text(size=13)) +
scale_colour_brewer(palette="Set1") +
scale_colour_manual(name = "Tmt",
                  labels = c("C", "S"),
                  values = c("red","blue"))+scale_linetype_manual(name = "Tmt",
                  labels = c("C", "S"),
                  values = c("solid","dashed"))

I am creating the following graph:

I want to make the linetypes clear in my legend. I'm not sure if my manual scaling of linetype hasn't worked, or whether it is because the width of the legend is too narrow. I have tried adding:

+guides(linetype=guide_legend(keywidth=5))

to adjust the width, but it doesn't work. Any one got any ideas how to resolve this issue?

Many thanks!

Answer 1

To change width of legend keys you should use the function theme() and argument legend.key.width= . You will also need package grid to set units.

library(grid)
+ theme(legend.key.width=unit(1,"cm"))

But in your particular case you need to make another change to your plot. As you are setting linetype=1 in geom_errorbar() both lines in legend will appear as solid. So you need to add argument show_guide=FALSE to geom_errorbar() .

  + geom_errorbar(aes(ymin=DV-Error, ymax=DV+Error),
                width = 0.1,linetype=1,
                   show_guide=FALSE)