You need to set drop=FALSE on both scales (fill and x) like this:
library(ggplot2)
df <- data.frame(type=c("A", "A", "A", "B", "B"), group=rep("group1", 5))
df1 <- data.frame(type=c("A", "A", "A", "B", "B", "A", "A", "C", "B", "B"), group=c(rep("group1", 5),rep("group2", 5)))
df$type <- factor(df$type, levels=c("A","B", "C"))
df1$type <- factor(df1$type, levels=c("A","B", "C"))
plt <- ggplot(df, aes(x=type, fill=type)) +
geom_bar(position='dodge') +
scale_fill_discrete(drop=FALSE) +
scale_x_discrete(drop=FALSE)
plt1 <- ggplot(df1, aes(x=type, fill=type)) +
geom_bar(position='dodge') +
scale_fill_discrete(drop=FALSE) +
scale_x_discrete(drop=FALSE)
Edit:
I’m pretty sure this works. Forgot to change x to type instead of group and the position=’dodge’! Just paste and test. The stat_bin deals with bins with zero counts. Check the docs.