Adjust ggplot legend - r

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

Answer 1

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()
)