Legends for separate lines and points

[willem vervoort]

I am relatively new to ggplot2 and I don't seem to be able to find an answer to how you create a legend if you plot two different y values in a plot.
Here is some example code similar to what I am trying to do
library(ggplot2)

x <- rep(runif(20),5)
y <- rnorm(100)
y2 <- mean(y) + sd(y)*x
treat <- ifelse(x > 0.5, "treat 1","treat 2")
crop <- ifelse(y > 0,"Fallow","Crop")

plot.frame <- data.frame(x = x, y = y, y2 = y2, treat = treat,
      crop = crop)
     
p <- ggplot(plot.frame, aes(x=x,y=y)) +
      geom_point(size=2,colour="black") +
      geom_line(aes(x=x,y=y2,colour="red"),colour="red",size=1) +
      facet_grid(crop~treat) +
      opts(labels = c(x = "Variable 1", y = "Variable 2"))

print(p)


I would like to have a legend next to the plot that says:
Legend title
"Points name"
"Line name"

I have searched through all the posts, but have not managed to figure it out. Any help is appreciated.
Regards
Willem
--
http://blogs.usyd.edu.au/waterhydrosu/

[Willem]

Found part of the answer myself, but I still can't get the points in
the legend. However, now I have got a legend for the line
Willem

library(ggplot2)

x <- rep(runif(20),5)
y <- rnorm(100)
y2 <- mean(y) + sd(y)*x
treat <- ifelse(x > 0.5, "treat 1","treat 2")
crop <- ifelse(y > 0,"Fallow","Crop")

plot.frame <- data.frame(x = x, y = y, y2 = y2, treat = treat,
crop = crop)

p <- ggplot(plot.frame, aes(x=x,y=y)) +
geom_point(size=2,colour="black") +

geom_line(aes(x=x,y=y2,colour="line"),size=1) +

facet_grid(crop~treat) +
opts(labels = c(x = "Variable 1", y = "Variable 2"))

p <- p + scale_colour_manual("Adjust",c("black"="black","line"="red"))

print(p)

[Hadley Wickham]

Hi Willem,

You were so close:

p <- ggplot(plot.frame, aes(x=x,y=y)) +

geom_point(aes(colour = "point"), size=2) +

geom_line(aes(x=x,y=y2,colour="line"),size=1) +
facet_grid(crop~treat) +
opts(labels = c(x = "Variable 1", y = "Variable 2"))

p <- p + scale_colour_manual("Adjust",c("point"="black","line"="red"))

Unfortunately the legend can't currently tell you only have red points
and black lines, but it's something I hope to fix in a future release.

Hadley

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