I need to add the theta greek letter in the x-axis label of this plot(s):
var=c("a", "b", "c")
df=data.frame(x=c(1:20),y=c(41:60))
df_plot=list()
for (i in 1:length(var)) {
df_plot[[i]]=ggplot()+
geom_line(data=df, aes(x=x, y=y))+
xlab(paste("theta ", var[i]))
}
How can I do it?
If I use expression() I get the letter but not the index i.


