ggplot2: Fix colors to factor levels

Question

I\'m working on a larger project for which I am creating several plots in ggplot2. The plots are concerned with plotting several different outcomes across several different

Answer 1

You could define your own custom scale, if you like. If you look at the source for scale_fill_manual,

scale_fill_manual
#> function (..., values) 
#> {
#>     manual_scale("fill", values, ...)
#> }
#> 

it's actually quite simple:

library(ggplot2)

scale_fill_chris <- function(...){
    ggplot2:::manual_scale(
        'fill', 
        values = setNames(c('green', 'blue', 'red', 'orange'), LETTERS[1:4]), 
        ...
    )
}

df1 <- data.frame(Value = c(40, 20, 10, 60), 
                  Type = c("A", "B", "C", "D"))

ggplot(df1, aes(x = Type, y = Value, fill = Type)) + 
    geom_col() + 
    scale_fill_chris()

df2 <- data.frame(Value = c(40, 20, 60), 
                  Type = c("A", "B", "D"))

ggplot(df2, aes(x = Type, y = Value, fill = Type)) + 
    geom_col() + 
    scale_fill_chris()

df3 <- data.frame(Value = c(40, 20, 10, 60), 
                  Type = c("A", "B", "C", "D"))
df3$Type <- factor(df3$Type, levels = c("D", "C", "B", "A"), ordered = TRUE)

ggplot(df3, aes(x = Type, y = Value, fill = Type)) + 
    geom_col() + 
    scale_fill_chris()