geom_vline colour option not working

[Robin Wilson]

Hi,

I'm a relative beginner with ggplot2, and I'm having a bit of a
problem. I'm using the code below to plot a graph, which has three
lines (for the three different values of Surface) and I want to add
vertical lines at three important x values. These lines appear, but I
used the colour parameter to tell them to be in grey, but that isn't
happening. They're appearing in a purple colour.

Also, a legend item called "gray80" gets added, as well as a separate
legend entitled "2", with just one entry called "2".

I must be doing something silly here. What is it?

Code:

library(ggplot2)

df = read.csv('Comparison Data.csv', header=T)

graph <- ggplot(df, aes(x = Wavelength, y = Diff, colour=Surface,
title="A graph - YAY!")) + geom_line()
graph <- graph + theme_set(theme_bw())
graph <- graph + geom_vline(aes(xintercept=c(545, 645, 825),
colour="grey80", size=2))
graph <- graph + labs(x = "Wavelength (nm)", y = "Percentage
Difference", colour= "Surface Type")
graph

Cheers,

Robin

[hadley wickham]

Hi Robin,

If you are _setting_ the colour, it should not be inside the aesthetic
_mapping_ specification:

geom_vline(aes(xintercept=c(545, 645, 825)), colour="grey80", size=2)

Hadley

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[Robin Wilson]

Hi Hadley,

Of course - that's where I went wrong.

Thanks for your very prompt reply, and also for the great tool which
is ggplot2.

Kind regards,

Robin