Using a for loop to save multiple ggplot as jpeg - r

Question

I'd like to save multiple ggplots as jpegs through a for loop. But when I've tried to adapt code I've written for a basic plot command, I get no output (nothing is saved to my working directory).
For Example, this works great:
library(cowplot)
library(ggplot)
X<-c(1,2,3,4,5,6,7,8,9)
Y1<-c(2,3,4,4,3,2,4,5,6)
Y2<-c(3,4,5,3,2,1,1,2,3)
Y3<-c(4,5,6,7,8,9,8,7,6)
DF<-data.frame(X,Y1,Y2,Y3)
for(i in 1:3){
jpeg(paste(i,".jpeg",sep=""))
plot(DF[,1],DF[,i+1])
dev.off()
}
I end up getting three jpeg files saved to my working directory.
I'm not sure how to properly index the ggplot call here for i, but even this should return 3 instances of the same plot:
for(i in 1:3){
jpeg(paste(i,".jpeg",sep=""))
ggplot(data=DF,aes(x=X,y=Y1))+geom_line()
dev.off()
}
In the end, I was hoping to combine multiple plots onto one jpeg, and then save multiple jpegs like this:
for(i in 1:3){
jpeg(paste(i,".jpeg",sep=""))
A<-ggplot(data=DF,aes(x=X,y=Y1))+geom_line()
B<-ggplot(data=DF,aes(x=X,y=Y2))+geom_line()
C<-ggplot(data=DF,aes(x=X,y=Y3))+geom_line()
plot_grid(A,B,C)
dev.off()
}
So this plot should also return 3 instances of the same plot, all with different indexed file names. But again, I get nothing.
So my question is why is there a difference between generic plotting and ggploting in this for loop. And how can one save mutliple jpegs from ggplots like above?

Answer 1

How about
library(gridExtra) # gridExtra::arrangeGrob
for(i in 1:3) {
jpeg(paste0(i, ".jpg"))
A <- ggplot(data = DF, aes(x = X, y = Y1)) + geom_line()
B <- ggplot(data = DF, aes(x = X, y = Y2)) + geom_line()
C <- ggplot(data = DF, aes(x = X, y = Y3)) + geom_line()
grid.arrange(arrangeGrob(A, B, C, ncol = 3))
dev.off()
}
Note: this solution does not produce the side annotations of cowplot ("A", "B", "C").

Answer 2

using your code:
for(i in 1:3){
jpeg(paste(i,".jpeg",sep=""))
A<-ggplot(data=DF,aes(x=X,y=Y1))+geom_line()
B<-ggplot(data=DF,aes(x=X,y=Y2))+geom_line()
C<-ggplot(data=DF,aes(x=X,y=Y3))+geom_line()
k<-plot_grid(A,B,C)
ggsave(k, filname = "path/finalplot.jpeg")
}
look at ?ggsave to look at other arguments to specify like height and width