r - change color of only one bar in ggplot

Question

I want to color only one bar in ggplot. This is my data frame:

area <- c("Pó?noc", "Po?udnie", "Wschód", "Zachód")
sale <- c(16.5, 13.5, 14, 13)
df.sale <- data.frame(area, sale)
colnames(df.sale) <- c("Obszar sprzeda?y", "Liczba sprzedanych produktów (w tys.)")

And code for plotting:

plot.sale.bad <- ggplot(data=df.sale, aes(x=area, y=sale, fill=area)) +
  geom_bar(stat="identity") +
  scale_fill_manual(values=c("black", "red", "black", "black")) +
  xlab(colnames(df.sale)[1]) +
  ylab(colnames(df.sale)[2]) +
  ggtitle("Porównanie sprzeda?y") 

I would like to have only one bar colored and 3 others to have default color (darkgrey, not black, it looks bad for me). How can I change color of only on bar or how to get name of the default color of bars to put them instead of black?

Answer 1

If you like having everything in the ggplot call, you can use an ifelse statement within factor() for the fill as shown below.

This also separates the legend into two categories (i.e. highlighted and not highlighted) so that you aren't repeating the values shown on the x axis. This also provides another illustrative dimension to the plot in the legend.

plot.sale.bad2 <- ggplot(data=df.sale,
                         aes(x=area,
                             y=sale,
                             fill=factor(ifelse(area=="Po?udnie","Highlighted","Normal")))) +
  geom_bar(stat="identity") +
  scale_fill_manual(name = "area", values=c("red","grey50")) +
  xlab(colnames(df.sale)[1]) +
  ylab(colnames(df.sale)[2]) +
  ggtitle("Porównanie sprzeda?y") 

plot.sale.bad2

If the legend isn't needed you can add show.legend = FALSE to the geom_bar() call to produce the following: