legend in ggplot for multiple lines

Is there really no simple way to add a legend when using ggplot() to plot multiple lines? I understand that the "right" tidyverse method is to pretend the two lines are the same variable and then add a category...i.e. switch to long format.

n <- 10
v1 <- rnorm(n)
v2 <- v1 + rnorm(n)
theData <- tibble(v1=v1, v2 = v2)
theData %>% ggplot(aes(x=v1)) +
  geom_line(aes(y=v2),color="red") +

# Would be nice to get a legend showing red line and blue points
# even if it's a silly example

Created on 2022-05-02 by the reprex package (v2.0.1)

theData %>% ggplot(aes(x=v1)) +
  geom_line(aes(y=v2,color="a")) +
  geom_point(aes(y=v2,color="b")) +
  scale_color_manual(values = c("a"="red","b"="blue"))
1 Like

Thanks @nirgrahamuk. That is exactly what I needed. I had done a bunch of searching around and you are the only one to give such a great answer.

In case it helps anyone else, I did a little looking around and you can augment @nirgrahamuk's answer to change the legend title by adding

+  guides(color=guide_legend("my title"))

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