[R] ggplot: colours to geom_segments

[John Kane]

> Paul Emberson
> "You need to map colour to a variable.  Try
> geom_segment(mapping=aes(colour=Food)) "

That did it.  Apparently I have not gotten to 'mapping' yet in the book!

> Thierry.ONKELINX
> You need to change colour = "darkgreen" into aes(colour = Food). This
> will give a different colour along Food.

Not exactly, Thierry, I wanted to change the line colours but your 
solution has solved my next problem which was to make the points and the
lines have the same colours.

Thanks to both of you.

Next Question  

How do I select colours rather than using the predetermined ones? I know that I should, at least, be able to use RColorBrewer but I have not figured out how yet.

Thanks again.

John

--- On Tue, 8/11/09, ONKELINX, Thierry <Thierry.ONKELINX at inbo.be> wrote:

> From: ONKELINX, Thierry <Thierry.ONKELINX at inbo.be>
> Subject: RE: [R] ggplot: colours to geom_segments
> To: "John Kane" <jrkrideau at yahoo.ca>, r-help at stat.math.ethz.ch
> Received: Tuesday, August 11, 2009, 5:35 AM
> Dear John,
> 
> You need to change colour = "darkgreen" into aes(colour =
> Food). This
> will give a different colour along Food.
> 
> HTH,
> 
> Thierry
> 
> ------------------------------------------------------------------------

> Just as an exercise I am tying to add colours to a
> geom_segment command.
> I can get one colour but not a sequence of colours.  
> Can anyone suggest how I can get the green lines in the
> plot below to be
> different colours?  I thought I could use a palatte of
> colours but that
> did not seem to work.
> 
> Thanks
> 
> ========================================================================
> =
> 
> library(ggplot2)
> 
> xx <- structure(list(Food = structure(c(2L, 1L, 3L, 4L),
> .Label =
> c("Bread", "Milk", "Potatoes", "Rice"), class = "factor"),
> Expense =
> c(25, 49, 34, 15)), .Names = c("Food", "Expense"),
> row.names = c(NA,
> -4L), class = "data.frame")
> 
> p <- ggplot(xx, aes(x = 0, xend = Expense,  y =
> Food, yend = Food)) pa
> <- p + geom_point(aes(Expense, Food)) + 
>    
>    geom_segment(colour="darkgreen") + 
>        xlab("Food") +
> geom_vline(xintercept=40, colour='red') pa



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