`geom_line()` connects points mapped to different groups

Question

I\'d like to group my data based on the interaction of two variables, but only map an aesthetic to one of those variables. (The other variable represents replicates

Answer 1

Your code works if you do the following. I think you had a problem because aes treated "treat" and "replicate" as vectors, so it was equivalent to group = 1.

ggplot(d, aes(x=x, y=y, colour=treatment, group=interaction(treatment, replicate))) + 
  geom_point() + geom_line()