R help - Apr 2012 - using for loops with ggplot

Hi all, I have been using ggplot for a few months and ran into this
porblem, I am trying to use ggplot in a for loop and it is not working. if
I do the following:
 data=as.data.frame(cbind(rnorm(10),rnorm(10),rnorm(10)))
############
pp=ggplot(data, aes(x=(1:10), y=data[,1]))
pp=pp+geom_line(aes(x=(1:10),y = data[,1]),lty=2)
pp=pp+geom_line(aes(x=(1:10),y = data[,2]),lty=2)
pp=pp+geom_line(aes(x=(1:10),y = data[,3]),lty=2)
print(pp)
############
I get what I want, all 3 lines on the plot,

but this does NOT work:
###################
pp=ggplot(data, aes(x=(1:10), y=data[,1]))
for(i in 1:3){
pp=pp+geom_line(aes(x=(1:10),y = data[,i]),lty=2)
}
print(pp)
################
this does not work...

I know I can do it using the group varable, but I would like to use for
loops sometimes and want to know if you can do it.

thank, Tarek

	[[alternative HTML version deleted]]

This is because of lazy evaluation.

Try this:

pp=ggplot(data, aes(x=(1:10), y=data[,1]))
for(i in 1:3){
pp=pp+geom_line(aes(x, y), data = data.frame(x=1:10,y = data[,i]),lty=2)
}
print(pp)

2012?4?5?14:36 Tarek Haddad <tarekdhaddad at
gmail.com>:
> pp=ggplot(data, aes(x=(1:10), y=data[,1]))
> for(i in 1:3){
> pp=pp+geom_line(aes(x=(1:10),y = data[,i]),lty=2)
> }
> print(pp)


-- 
--
Kohske Takahashi <takahashi.kohske at gmail.com>

Research Center for Advanced Science and Technology,
The University of  Tokyo, Japan.
http://www.fennel.rcast.u-tokyo.ac.jp/profilee_ktakahashi.html