Adjust ggplot legend

Question

I am trying to make the following changes to the ggplot below (partly illustrated in the picture provided):

change shading legend to show economic cycle (shaded is a recession, no shade is an expansion)
add additional legend to show economic variables (green is 'CLI' and red is 'Inflation Expectations")

The code so far looks like this:

A <- ggplot(Alldata, aes(Date)) + 
  geom_tile(aes(alpha = Recession, y = 1), 
            fill = "grey", height = Inf) +
  scale_alpha_continuous(range = c(0, 1), breaks = c(0, 1))+
  geom_line(aes(y = stdINFEX), col = 'blue', size = .8)+
  ylab('')+
  theme(        axis.text.y=element_blank(),  #remove y axis labels
        axis.ticks.y=element_blank()  #remove y axis ticks
  )

    
A

B <- A + geom_line(aes(y = CLI), col = 'green', size = .8) 

B

ggplot

score 0 · Answer 1 · answered Oct 12 '21 at 18:43

Maybe this is what you are looking for:

You could set the labels for legend entries via the labels argument of the scale, e.g. using a named vector you could assign a label Expansion to the value "0"
To get a legend for your lines you have to map on aesthetics, i.e. move color=... inside of aes(). Note that using color names inside aes() is meaningless. Therefore I would suggest to use meaningful labels. You could then set your desired colors via scale_color_manual.
Finally, to set the labels for your legends you could make use of labs()

As you provided no example data (see how to make a minimal reproducible example) I make use of the ggplot2::economics dataset as example data:

library(ggplot2)

set.seed(123)

economics$Recession <- 0
economics$Recession[sample(1:nrow(economics), 100)] <- 1

ggplot(economics, aes(date)) +
  geom_tile(aes(alpha = Recession, y = 1),
    fill = "grey", height = Inf
  ) +
  scale_alpha_continuous(range = c(0, 1), 
                         breaks = c(0, 1), 
                         labels = c("0" = "Expansion", "1" = "Recession")) +
  geom_line(aes(y = psavert, color = "psavert"), size = .8) +
  geom_line(aes(y = uempmed, color = "uempmed"), size = .8) +
  scale_color_manual(values = c(psavert = "blue", uempmed = "green")) +
  labs(y = NULL, alpha = "Economic Cycle", color = "Economic Variable") +
  theme(
    axis.text.y = element_blank(),
    axis.ticks.y = element_blank() 
  )

That definitely did the trick! How could you avoid changing the name of the variable 'uempmed' in the data set, but in the legend you it displays 'Unemployment of Med Students' ? — MacroChair, Oct 12 '21 at 20:06
Similar to setting the labels for the alpha scale you could do `scale_color_manual(...., labels = c(psavert = "Personal savings rate", uempmed = "Median duration of unemployment"))`. BTW: The labels I haven chosen are probably misleading. They don't refer to the names columns in the dataset, i.e. change the names in the dataset will have no effect on the legend. Instead of using e.g. ` psavert` you could use `color="save"` and then do `values = c(save = "...)`. — stefan, Oct 12 '21 at 20:26

Adjust ggplot legend

1 Answers1