How to create a faceted line-graph using ggplot?

Question

I have a data frame created with this code:

require(reshape2) foo <- data.frame( abs( cbind(rnorm(3),rnorm(3, mean=.8),rnorm(3, mean=.9),rnorm(3, mean=1)))) qux <- data.frame( abs( cbind(rnorm(3),rnorm(3, mean=.3),rnorm(3, mean=.4),rnorm(1, mean=2)))) bar <- data.frame( abs( cbind(rnorm(3,mean=.4),rnorm(3, mean=.3),rnorm(3, mean=.9),rnorm(3, mean=1))))  colnames(foo) <- c("w","x","y","z") colnames(qux) <- c("w","x","y","z") colnames(bar) <- c("w","x","y","z")  rownames(foo) <- c("n","q","r") rownames(qux) <- c("n","q","r") rownames(bar) <- c("n","q","r")  foo <- cbind(ID=rownames(foo),foo) bar <- cbind(ID=rownames(bar),qux) qux <- cbind(ID=rownames(bar),qux)  foo$fn <- "foo" qux$fn <- "qux" bar$fn <- "bar"  alldf<-rbind(foo,qux,bar) alldf.m <- melt(alldf) 

What I want to do is to create a ggplot line curve in facet format, so it creates a graph like this:

The actual graph does not contain upward lines - this is just a sketch so that the line separation is clear.

My current code doesn't work:

    library(ggplot2)     p <- ggplot(data=alldf.m, aes(x=variable)) +             geom_line(aes(colour=ID),alpha=0.4)     p <- p + facet_wrap( ~ fn)     p 

What's the best way to do it?

Answer 1

Try this:

ggplot(data=alldf.m, aes(x=variable, y = value, colour = ID, group = ID)) +    geom_line() + facet_wrap(~fn) 

Answer 2

Even it is a ggplot2 is required by the OP , but I think this example is suitable for lattice also:

library(lattice) xyplot(data=alldf.m, value~variable|fn, type ='b', groups = ID, auto.key = T) 

and using latticeExtra we can get something colse to ggplot2 solution:

 p <-  xyplot(data=alldf.m, value~variable|fn, type ='b', groups = ID, auto.key = T)  update(p , par.settings = ggplot2like())