Specific Variable Color in ggplot

Question

Let\'s say I have the following data set:

set.seed(1)
df <- data.frame(
  Index = 1:10,
  Heat = rnorm(10),
  Cool = rnorm(10),
  Other = rnorm(10),
  a = rno         


        

Answer 1

Something like the following might work. First I set up the colour scale:

plot_data <- tidyr::gather(df, key = 'Variable', value = 'Component', -Index)
vars <- levels(plot_data$Variable)
colours <- character(length(vars))
colours[vars=="Heat"] <- "red"
colours[vars=="Cool"] <- "blue"
colours[vars=="Other"] <- "green"
other_colours <- c("orange", "purple", "brown", "gold")
others <- !(vars %in% c("Heat", "Cool", "Other"))
colours[others] <- other_colours[1:sum(others)]

The idea is to manually assign your desired colours first, and then assign colours from some list to the other elements. If you need more colours for other_colours, you can get a complete list of named colours using colours().

Then the plot is produced by:

ggplot(plot_data, aes(Index, Component, colour = Variable)) + 
          geom_line() +
          scale_colour_manual(values = colours)

I don't think that it is possible to use scale_colour_manual and still let ggplot pick some colours automatically.