Colour stacked bar-chart with unique colour for each bar in ggplot

Question

I would like to make a stacked histogram in ggplot, where each of the bars (and stacked bars) have a unique colour - using a provided hex value.

For example, take this dataframe.

Pct <- c(0.8026200, 0.1973800, 0.8316421, 0.1683579)
Site <- c("A","A","B", "B")
hex <- c("#53412F", "#B4A383", "#4E3B29", "#B6A37E")
bin <- rep(c(1,2), 2)

df <- as.data.frame(cbind(Site,Pct,hex,bin))

I would like to use the hex colours specified to colour the corresponding bars.

I have tried variations along these lines:

ggplot()+
  geom_bar(aes(y=Pct, x=as.character(Site), fill=bin), data=df, stat="identity")+
  theme_bw() +
  scale_fill_manual("Subject", values=df$hex)

but this produces a green and red colour for each plot?

Any help would be greatly appreciated. Sorry if it is a simple solution - I have not got much experience with stacked barcharts.

Thank you in advance!

Very similar to this SO question: stackoverflow.com/questions/59430088/… — TheSciGuy
Does this answer your question? Best way to make a black and white ggplot bar plot with multiple stacked sections in your bars? — TheSciGuy

Francois51 Francois51 · Accepted Answer · 2020-02-21T14:51:42

your issue comes from a little contradiction I think : you say to ggplot to attribute the aesthetic "fill" using the variable "bin". Since "bin" only have two possibility ("1" or "2"), ggplot uses only 2 colors. It uses the two firsts, which are green and red.

I am not sure what you exactly want, but if you want a distinct color for each bar, then you have either to change "bin" like in the example below, or to give another argument to "fill", for example you can just replace "fill = bin" by "fill = hex". But if you want 4 colors, then the variable used in "fill" has to have 4 different values (below, I choosed "bin", and the values are 1,2,3,4).

Example :

Pct <- c(0.8026200, 0.1973800, 0.8316421, 0.1683579)
Site <- c("A","A","B", "B")
hex <- c("#53412F", "#B4A383", "#4E3B29", "#B6A37E")

##bin is defined in order it has a different value for each bar
bin <- c(1,2,3,4)
df <- as.data.frame(cbind(Site,Pct,hex,bin))

ggplot()+
  geom_bar(aes(y=Pct, x=as.character(Site), fill=bin)
           , data=df, stat="identity")+
  theme_bw() +
  scale_fill_manual(values=hex)

Result:

Hope it will clarify your problem!

Colour stacked bar-chart with unique colour for each bar in ggplot

1 Answers