ggplot2: Changing the order of stacks on a bar graph

Question

I'm trying to make a stacked bar graph with a facet_wrap, but I want the order of my stacked variables ("developed") to be flipped. I've reordered the factors, and tried "order=descend()," as well as "scale_fill_manual" and nothing seems to work.

Here is my code:

developed=rep(c("developed","available"),6)
agriculture=rep(c(rep("loi",2), rep("dryland",2), rep("agroforestry",2)),2)  
acres=c(7435,24254,10609,120500,10651,75606,6037,9910,4390,895,9747,46893)
islands=c(rep("All islands",6), rep("Oahu",6))
all_is2=data.frame(developed, agriculture, acres, islands)
head(all_is2)
  developed  agriculture  acres      island
1 developed          loi   7435 All islands
2 available          loi  24254 All islands
3 developed      dryland  10609 All islands
4 available      dryland 120500 All islands
5 developed agroforestry  10651 All islands
6 available agroforestry  75606 All islands

changing factor levels of "agriculture" and "developed"

all_is2$agriculture=factor(all_is2$agriculture,levels=c("loi","dryland","agroforestry"))
all_is2$developed=factor(all_is2$developed,levels=c("developed","available"))
levels(all_is2$developed)
[1] "developed" "available"

Then, plotting:

ggplot(all_is2,aes(x=agriculture,y=acres,fill=developed))+
     geom_bar(position="stack", stat="identity")+
     facet_wrap(~islands)+ scale_fill_grey(start=0.8, end=0.2, name="")+ xlab("")+ylab("Acres")+theme_bw()+ scale_y_continuous(labels=comma)

I want the "developed" parts of the bars in gray on top of the "available" parts of the bars, which are black. And the legend should match the order of the bars as well.

Also, is it possible to move the facet_wrap "All islands" and "Oahu" at the top to the bottom of the graph under "loi" "dryland" and "agroforestry." Thank you for your help!!

Answer 1

This might be a solution.

What I did was ordering the dataset, so that the value I wanted to appear closest to the x-axis appeared first in the dataset. (I've used your ordering of factors here). This fixt the positioning of the bars.

Then, we had to change the colors and order of the legend. I could not wrap my head around scale_fill_grey, so I changed it to scale_fill_manual instead, setting both values and breaks.

ggplot(all_is2[rev(order(all_is2$developed)),] ,aes(x=agriculture,y=acres,fill=developed))+
  geom_bar(position="stack", stat="identity")+theme_bw()+
  facet_wrap(~islands)+ 
  scale_fill_manual(values=c(developed="grey80",available="grey20"),name="",
                    breaks=c("developed","available"))+
 xlab("")+ylab("Acres")

I don't know if it's a bug or a feature, and I think this also happened with previous versions in ggplot, but it appears that with stat_identity the first observation is plotted closest to the x-axis, the second on top of that etc.

Demonstration:

set.seed(123)
testdat <- data.frame(x=1,y=sample(5))


p1 <- ggplot(testdat, aes(x=x,y=y,fill=factor(y))) +geom_bar(stat="identity")+labs(title="order in dataset")
p2 <- ggplot(testdat[order(testdat$y),],aes(x=x,y=y,fill=factor(y))) +
  geom_bar(stat="identity") + labs(title="ordered by y")
p3 <- ggplot(testdat[rev(order(testdat$y)),],aes(x=x,y=y,fill=factor(y))) +
  geom_bar(stat="identity") + labs(title="reverse ordered by y")

Answer 2

Fwiw, here is a solution with dplyr, and it uses scale_fill_manual to be explicit about the colors:

library(ggplot2)
library(dplyr)

developed=rep(c("developed","available"),6)
agriculture=rep(c(rep("loi",2), rep("dryland",2), rep("agroforestry",2)),2)  
acres=c(7435,24254,10609,120500,10651,75606,6037,9910,4390,895,9747,46893)
islands=c(rep("All islands",6), rep("Oahu",6))
all_is2=data.frame(developed, agriculture, acres, islands)

all_is2$agriculture=factor(all_is2$agriculture,levels=c("loi","dryland","agroforestry"))
#all_is2$developed=factor(all_is2$developed,levels=c("available","developed"))

all_is3 <- all_is2 %>% group_by(islands,agriculture,developed) %>% 
                       summarize(acres=sum(acres)) 

ggplot(all_is3,aes(x=agriculture,y=acres,fill=developed))+
  geom_bar(position="stack", stat="identity")+
  facet_wrap(~islands)+ 
  xlab("")+ylab("Acres")+theme_bw() +
  scale_fill_manual(name="",values=c("available"="black","developed"="light gray"))