Thick line ggplot

Question

How can you build one line thicker than another. I tried using geom_line(size=X) , but then this increases the thickness of both lines. Say, I would like to increase the thickness of the first column, how could I approach this?

 a <- (cbind(rnorm(100),rnorm(100))) #nav[,1:10] sa <- stack(as.data.frame(a)) sa$x <- rep(seq_len(nrow(a)), ncol(a)) require("ggplot2") p<-qplot(x, values, data = sa, group = ind, colour = ind, geom = "line") p + theme(legend.position = "none")+ylab("Millions")+xlab("Age")+ geom_line( size = 1.5) 

Answer 1

You need to match the thickness of the string to a variable:

 p + geom_line(aes(size = ind)) 

To control the thickness, use scale_size_manual() :

 p + geom_line(aes(size = ind)) + scale_size_manual(values = c(0.1, 1))