Add legend to ggplot2 bar plot

June 30, 2022

note that this question differs from Add legend to ggplot2 line plot. This is a multiple bar plot and the answers provided for line plots dont apply.

How can I add a legend to the below?

library(tidyr);library(ggplot2)   
date <- 2001:2050
dat1 <- 1:50
dat2 <- 50:1
data <- tibble(date, dat1, dat2)
p2 <- ggplot(data, aes(x=date)) +
  geom_bar(aes(y=dat1, color = "orange"), stat = "identity", fill="orange")+
  geom_bar(aes(y=dat2,color = "blue"), stat = "identity", fill="blue")+
  ggtitle("dat") + 
  ylab("unit") 
p2

As you can see the default legends and bars are wrongly filled.

This was closed wrongfully, again.

>Solution :

library(tidyverse)

date <- 2001:2050
dat1 <- 1:50
dat2 <- 50:1
data <- tibble(date, dat1, dat2)

data %>%
  pivot_longer(c(dat1, dat2)) %>%
  ggplot(aes(date, value, fill = name)) +
  geom_col(position = position_identity())+
  scale_fill_manual(values = c("orange", "blue")) +
  ggtitle("dat") + 
  ylab("unit") +
  theme(axis.text.x = element_text(angle = 45, vjust = 0.5, hjust=1))