I\'ve tried several suggestions based on several posts on here, as well as reading through the ggplot2 documentation, but this question is slightly different, and I haven\'t
You can use the interaction between d and b:
p <- ggplot(temp, aes(x=interaction(d, b), y=c, fill=d, colour=d))+ theme_classic()+
geom_point()
p + geom_line(aes(group=a),colour=1)
with correct x axis. Convert the x to numeric and set new labels
p <- ggplot(temp, aes(x=as.numeric(interaction(d,b)), y=c, fill=d, colour=d))+ theme_classic()+
geom_point()
p <- p + geom_line(aes(group=a),colour=1)
p + scale_x_continuous(breaks = c(1.5,3.5,5.5), labels = levels(temp$b))