Mixed Variable Stacked Barplot - r

Question

I would like to produce a GGPlot stacked barplot with variables on the horizontal axis, yet some variables have different responses.
Some variables are 'Y/N' responses. Some variables are 'Old/Young'. And some of the variables are a Likert scale of 0-5.
Therefore, I would like to plot these in a stacked barplot form, with each variable type encoded with a different colour palette, and with a legend reflecting the different palettes/variable types.
I wondered if someone could help with this, please? Would be greatly appreciated.
X1<-c("N","N","N","N","Y","N","Y","N","N","N","N","N","Y","N","N","Y","N","N","N","Y","N","Y","Y","N","N","Y","Y","Y","N","N","N","N","N","N","N","N","Y","N","Y","N","N","N","N","Y","N","N","Y","N","Y","Y","N","Y","N","N")
X2 <-c("N","N","N","N","Y","N","Y","N","N","N","N","N","Y","N","N","Y","N","N","N","Y","N","Y","Y","N","N","Y","Y","Y","N","N","N","N","N","N","N","N","Y","N","Y","N","N","N","N","Y","N","N","Y","N","Y","Y","N","Y","N","N")
X3<-c(1,1,0,1,2,0,0,0,0,0,1,1,1,2,0,1,2,1,1,0,0,0,4,1,0,0,0,0,1,0,2,0,0,2,1,1,0,0,0,1,1,0,1,0,1,0,1,1,0,1,0,1,1,1)
X4 <-c("YouNg","Old","Old","YouNg","Old","Old","Old","YouNg","YouNg","YouNg","Old","Old","Old",
"Old","Old","Old","Old","YouNg","Old","Old","Old","YouNg","YouNg","Old","Old","Old",
"Old","Old","Old","Old","Old","Old","Old","YouNg","Old","YouNg","Old","YouNg","Old",
"Old","YouNg","Old","YouNg","YouNg","Old","Old","Old","YouNg","Old","Old","Old","YouNg", "Old", "Old")
Y <- data.frame(X1, X2, X3, X4)

Answer 1

One option to achieve your desired result would to use the ggnewscale package which allows for multiple scales and legends for the same aesthetic:
library(ggplot2)
library(ggnewscale)
library(tidyr)
library(dplyr)
dat <- Y |>
mutate(across(everything(), as.character)) |>
pivot_longer(everything(), names_to = "var")
ggplot(dat, aes(y = var)) +
geom_bar(data = ~subset(.x, var %in% c("X1", "X2")), aes(fill = value), position = "fill") +
scale_fill_brewer(palette = "Accent", guide = guide_legend(order = 3))+
new_scale_fill() +
geom_bar(data = ~subset(.x, var %in% c("X3")), aes(fill = value), position = "fill") +
scale_fill_brewer(palette = "Dark2", guide = guide_legend(order = 2)) +
new_scale_fill() +
geom_bar(data = ~subset(.x, var %in% c("X4")), aes(fill = value), position = "fill") +
scale_fill_brewer(palette = "Paired", guide = guide_legend(order = 1))
EDIT Depending on what you want to achieve there are three arguments to consider:
Use position = position_fill(reverse = TRUE) in geom_bar to reverse the order of the stack
To reverse the order of the fill colors use direction=-1 in scale_fill_xxx
Finally, if you want to reverse the order in the legend use reverse=TRUE in guide_legend.
The example code below uses all three, i.e.
the bars run from 0 on the left to 4 on the right.
the fill colors are reversed so that 0 is now assigned "pink" and 4 the "green" color
and finally the order in the legend is reversed.
ggplot(dat, aes(y = var)) +
geom_bar(data = ~subset(.x, var %in% c("X1", "X2")), aes(fill = value), position = "fill") +
scale_fill_brewer(palette = "Accent", guide = guide_legend(order = 3))+
new_scale_fill() +
geom_bar(data = ~subset(.x, var %in% c("X3")), aes(fill = value), position = position_fill(reverse = TRUE)) +
scale_fill_brewer(palette = "Dark2", guide = guide_legend(order = 2, reverse = TRUE), direction = -1) +
new_scale_fill() +
geom_bar(data = ~subset(.x, var %in% c("X4")), aes(fill = value), position = "fill") +
scale_fill_brewer(palette = "Paired", guide = guide_legend(order = 1))