fill aesthetic shouldn't appear in x-axis labels

[richierocks]

The variable used for the fill color shows up in labels on the x-axis. I'm not sure if it is ever desirable for that to happen, but here's an example where it isn't.

I thought it would be useful to show a confusion matrix using a mosaic plot. Here's a reproducible example.

library(dplyr)
library(ggplot2)
library(ggmosaic)

# Some sample data
set.seed(19790801)
actual <- iris$Species
predictions <- sample(iris$Species)

confusion <- table(actual, predictions) %>% 
  as.data.frame() %>% 
  mutate(
    is_correct = ifelse(
      actual == predictions, 
      "Correct prediction", 
      "Incorrect prediction"
    )
  )

ggplot(confusion) +
  geom_mosaic(
    aes(
      weight = Freq, 
      x = product(actual, predictions), 
      fill = is_correct
    )
  ) +
  theme(axis.text.x = element_text(angle = 45, hjust = 1))

I expected the x-axis labels to be levels ofactual (setosa/versicolor/virginica), but they are actually combinations of is_correct (Correct prediction/Incorrect prediction) and predictions (setosa/versicolor/virginica).

• Is this a bug?
• Did I just specify the aesthetics incorrectly?
• Is it possible to not show fill aesthetic values in x-axis labels?