How to make frequency barplot in groups?

Question

Suppose my data is two columns, one is "Condition", one is "Stars"

food <- data.frame(Condition = c("A", "B", "A", "B", "A"), Stars=c('good','meh','meh','meh','good'))

How to make a barplot of the frequency of "Star" as grouped by "Condition"?

I read here but would like to expand that answer to include groups.

for now I have

q <- ggplot(food, aes(x=Stars))
q + geom_bar(aes(y=..count../sum(..count..)))

but that is the proportion of the full data set.

How to make a plot with four bars, that is grouped by 'Condition'?

Eg. 'Condition A' would have 'Good' as 0.66 and 'Meh' as 0.33

Answer 1

I guess this is what you are looking for:

food <- data.frame(Condition = c("A", "B", "A", "B", "A"), Stars=c('good','meh','meh','meh','good'))
library(ggplot2)
library(dplyr)
data <- food %>% group_by(Stars,Condition) %>% summarize(n=n()) %>% mutate(freq=n/sum(n)) 

ggplot(data, aes(x=Stars, fill = Condition, group = Condition)) + geom_bar(aes(y=freq), stat="identity", position = "dodge")

At first i have calculated the frequencies using dplyr package, which is used as y argument in geom_bar(). Then i have used fill=Condition argument in ggplot() which divided the bars according to Condition. Additionally i have set position="dodge" to get the bars next to each other and stat="identity", due to already calculated frequencies.

Answer 2

I have used value ..prop.., aesthetic group and facet_wrap(). Using aesthetic group proportions are computed by groups. And facet_wrap() is used to plot each condition separately.

require(ggplot2)

food <- data.frame(Condition = c("A", "B", "A", "B", "A"),
                   Stars=c('good','meh','meh','meh','good'))

ggplot(food) +
  geom_bar(aes(x = Stars, y = ..prop.., group = Condition)) +
  facet_wrap(~ Condition)