Section 4.5, broom::augment does not create .resid feature in the resulting data frame

[guidothekp]

Start with the following code from the section titled "Constant variance among residuals".

df1 <- broom::augment(cv_model1$finalModel, data = ames_train)

The code that follows from the page does not work:

p1 <- ggplot(df1, aes(.fitted, .resid)) + 
  geom_point(size = 1, alpha = .4) +
  xlab("Predicted values") +
  ylab("Residuals") +
  ggtitle("Model 1", subtitle = "Sale_Price ~ Gr_Liv_Area")

This is because .resid is not listed as a column in df1. This can be checked by invoking names(df1).

To fix this, I had to modify the following line to the first piece of code shown above -- I had to add the .resid column.

df1 <- broom::augment(cv_model1$finalModel, data = ames_train) %>%mutate(.resid = Sale_Price - .fitted)