ggplot: How to display multiple groups via color and shape with point and line

Question

I want to draw a point-line chart of x-y-variables and highlight two groupings. I know some of the options to distinguish factors, like fill, shape, col or group. For the first group I would like to have color and for the second shape (which may or may not have the same color). And I need a legend to distinguish both groupings (which I already have). Perhaps I have to put aes in geom_line or geom_point, but I'm not sure. Since later on I would like to adjust size of the shapes (to better distinguish those).

How to connect those points by colored lines?
How to adjust size of the shape group?

Here is my code:

library(ggplot2) 
data <- data.frame(id1=c(1,1,1,2,2,2,3,3,3,4,4,4), 
                  id2=seq(1:3), year=seq(from=2007, to=2018, by=1),
                  variable=rep(c(5:8), each=3))

# two groups by color and shape, but it drops the line (seperate legends, thats nice)
ggplot(data, aes(x=year, y=variable, col=factor(id1), shape=factor(id2))) + 
  geom_line() + geom_point()

You can add aes(group = id1) to the geom_line to connect them by group. Adding something like size = 2 outside of the aes call will change the size of points/lines. — svenhalvorson

Allan Cameron Allan Cameron · Accepted Answer · 2020-03-06T13:59:50

Based on further information in comments from the OP, we are looking for something like this:

ggplot(data, aes(x=year, y=variable, col=factor(id1))) + 
  geom_line() + 
  geom_point(aes(shape=factor(id2), size = factor(id2))) + 
  labs(shape = "group 2", colour = "group 1", size = "group 2")

ggplot: How to display multiple groups via color and shape with point and line

1 Answers