Question

I am trying to change the colours on a ggplot column chart. After googling, I thought that the following code would work:

require(ggplot2)
require(RColorBrewer)
State <- c(rep("NSWTC",5), rep("TCV",5), rep("QTC",5), 
           rep("WATC",5), rep("SAFA",5), rep("Other",5))

Year  <- rep(c("11-12","12-13","13-14","14-15","15-16"),6)

##some random data
Funding.Programme <- abs(rnorm(30))

df <- data.frame(State, Year, Funding.Programme)

##this line makes the graph in the order you inputted it, rather than alphabetical
df$State <- factor(df$State, levels=unique(df$State))

##ugly coloured
bars <- ggplot(df) + 
            aes(x=Year ,y=Funding.Programme, fill=Year) + 
            geom_bar(stat='identity') + 
            facet_grid(facets=~State) + 
            scale_y_continuous('Gross Issuance Requirements')

##nicely coloured
blues <- brewer.pal(5, "Blues")
blues <- rev(blues)
##the following two graphs have the same colours
bars <- ggplot(df) + 
            aes(x=Year ,y=Funding.Programme, fill=Year) + 
            geom_bar(stat='identity') + 
            facet_grid(facets=~State) + 
            scale_y_continuous('Gross Issuance Requirements') + 
            scale_fill_brewer(blues)
bars
bars <- ggplot(df) + 
            aes(x=Year ,y=Funding.Programme, fill=Year) + 
            geom_bar(stat='identity') + 
            facet_grid(facets=~State) + 
            scale_y_continuous('Gross Issuance Requirements') + 
            scale_fill_brewer(blues.rev)
bars

##and this does not adjust the default colours
bars <- ggplot(df)+ 
            aes(x=Year,y=Funding.Programme, fill=Year) + 
            geom_bar(stat='identity') + 
            facet_grid(facets=~State) + 
            scale_y_continuous('Gross Issuance Requirements') + 
            scale_colour_manual(values = blues.rev)
bars

But the last method does not work, and the second and third-last charts produced are identical, despite the order of colours being reversed in the object.

Answer 1

You want scale_fill_manual(values = blues) or conversely with blues.rev (which you didn’t actually create in your example code, which I assume is a typo).

Only use scale_*_brewer when you’re selecting one of the default palette’s by name. Otherwise, use scale_*_manual for this sort of thing.

The last one doesn’t work because you were using colour instead of fill.

Finally, carriage returns and tabs: love them, cherish them, use them!