NULL defaults
The cut() function used by cut_by_quantile() can automatically provide sensible labels for each category. The code to generate these labels is pretty complicated, so rather than appearing in the function signature directly, its labels argument defaults to NULL, and the calculation details are shown on the cut() help page (docs).
This exercise is part of the course
Introduction to Writing Functions in R
Exercise instructions
- Update the definition of
cut_by_quantile()so that thelabelsargument defaults toNULL. - Remove the
labelsargument from the call tocut_by_quantile().
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Set the default for labels to NULL
cut_by_quantile <- function(x, n = 5, na.rm = FALSE, labels, interval_type) {
probs <- seq(0, 1, length.out = n + 1)
qtiles <- quantile(x, probs, na.rm = na.rm, names = FALSE)
right <- switch(interval_type, "(lo, hi]" = TRUE, "[lo, hi)" = FALSE)
cut(x, qtiles, labels = labels, right = right, include.lowest = TRUE)
}
# Remove the labels argument from the call
cut_by_quantile(
n_visits,
labels = c("very low", "low", "medium", "high", "very high"),
interval_type = "(lo, hi]"
)