Question

With this approach. I have a line plot graph. I want to plot ‘two’ line plot on the same graph. How can I simply add that data,

The data is in the form

1  5  10
2  8  20
3  9  30

I want to plot the X as column1 and the other two columns along the y axis.

-----
 # Commands
  2
  3 library(ggplot2)
  4
  5 req <- read.table("stats_quick_sort.dat")
  6
  7 summary(req)
  8
  9 xx <- req$V1
 10 yy <- req$V2
 11
 12
 13 png('stats_sort_image.png', width=800, height=600)
 14 gg <- qplot(xx, yy) + geom_line()
 15 print(gg)
 16 dev.off()

Answer 1

As an aside — if you provide a reproducible example that demonstrates your problem, it is much easier for us to help you. I’m going to give you a reproducible example as an answer so you see what I mean. It means anyone can copy and paste the code and it’ll work (whereas I couldn’t copy/paste your code because I don’t have stats_quick_sort.dat).

To plot multiple lines on a plot you just call geom_line again, feeding in the x and y variables to aes:

# generate some dummy data so this example can be reproduced
xx  <- sort(runif(20))
yy  <- runif(20)
yy2 <- runif(20)

gg <- qplot(xx, yy) + geom_line()        # first line
gg <- gg + geom_line(aes( x=xx, y=yy2 )) # add the second line!
print(gg)

In general, if you want to add other information to your plot that you did not supply in the initial qplot/ggplot call, then just feed it in to aes. You want a line? Use geom_line. You want new x and y coordinates? Then use geom_line(aes(x= .., y=..)). And so on.