ggplot geom_col legend not showing

Question

I am trying to show a legend to accompany a plot created using ggplot and geom_col - my legend isn't showing up. I originally plotted these data using geom_bar (with a visible legend but some other problems), but after more research it seems more appropriate to use geom_col.

I know this topic has a ton of google-able questions and answers, but after many searches and code variations I still have no success.

How can I make my legend visible?

My reproducible code is below.

site <- c(0.700, 0.854)
site <- lapply(site, function(x) round((x*100),1)) 
site <- unlist(site, use.names=FALSE) 
state <- c(0.726, 0.808)
state <- lapply(state, function(x) round((x*100),1)) 
state <- unlist(state, use.names=FALSE)
measure <- c("Individual", "Coalition")
measure <- unlist(measure, use.names=FALSE)
df1 <- data.frame(site,state,measure)
df2 <- melt(df1, id.vars='measure')
df2$variable <- factor(df2$variable,
                       levels = c('state','site'),ordered = TRUE)
fillcolors <- c("#7189A6", "#817BB0", "#7189A6", "#817BB0")

myplot <- 
  ggplot(df2, aes(measure, value, group = variable)) +
  geom_col(width=.75, position=position_dodge(width=0.80), fill=fillcolors)     +
  labs(title = paste0("Knowledge & Skills Gained", paste0(rep("", 0), collapse = " ")), 
      x = "", y = "", fill="") +
  scale_y_continuous(limits=c(0,100), labels = function(x){ paste0(x, "%")     }) +
  coord_flip() +
  geom_text(aes(label=(paste0(value,"%"))), size=3,
        colour = "#57585a",
        position=position_dodge(width=0.75), vjust=.3, hjust=-.1) +
  theme(legend.position="right", title = element_text(colour = "#57585a"),
        legend.text = element_text(colour="#57585a", size = 9))

  myplot

This results in the following plot: myplot

Thank you in advance!

Answer 1

The main issue is that you should use fill=, not group=:

  ggplot(df2, aes(measure, value, fill = variable)) +
  geom_col(width=.75, position=position_dodge(width=0.80))     +
  labs(title = paste0("Knowledge & Skills Gained", paste0(rep("", 0), collapse = " ")),
       x = "", y = "", fill="") +
  scale_y_continuous(limits=c(0,100), labels = function(x){ paste0(x, "%")     }) +
  coord_flip() +
  geom_text(aes(label=(paste0(value,"%"))), size=3,
            colour = "#57585a",
            position=position_dodge(width=0.75), vjust=.3, hjust=-.1) + 
  scale_fill_manual(values = c("#817BB0", "#7189A6")) +   
  guides(fill = guide_legend(reverse=T))

(There are a lot of other ways in which your code could be cleaned up; I focused only on getting the legend to appear.)