[R] ggplot inside cycle

[Petr PIKAL]

Dear all

I want to save several ggplots in one pdf document. I tried this

for (i in names(iris)[2:4]) {
p<-ggplot(iris, aes(x=Sepal.Length, y=iris[,i], colour=Species))
p+geom_point(aes(size=3))
}

with different variations of y input but was not successful. In past I 
used qplot in similar fashion which worked

for(i in names(mleti)[7:15]) print(qplot(sito, mleti1[,i], 
facets=~typ,ylab=i, geom=c("point", "line"), colour=ordered(minuty), 
data=mleti1))

So I wonder if anybody used ggplot in cycle and how to solve input of 
variables throughout cycle

Thank you

Petr