Fixing function arguments

The harmonic mean function is almost complete. However, you still need to provide some checks on the na.rm argument. This time, rather than throwing errors when the input is in an incorrect form, you are going to try to fix it.

na.rm should be a logical vector with one element (that is, TRUE, or FALSE).

The assertive package is loaded for you.

This exercise is part of the course

Introduction to Writing Functions in R

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Exercise instructions

Update calc_harmonic_mean() to fix the na.rm argument by using use_first() to select the first na.rm element, and coerce_to() to change it to logical.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

# Update the function definition to fix the na.rm argument
calc_harmonic_mean <- function(x, na.rm = FALSE) {
  assert_is_numeric(x)
  if(any(is_non_positive(x), na.rm = TRUE)) {
    stop("x contains non-positive values, so the harmonic mean makes no sense.")
  }
  # Use the first value of na.rm, and coerce to logical
  ___ <- ___(___(___), ___ = "___")
  x %>%
    get_reciprocal() %>%
    mean(na.rm = na.rm) %>%
    get_reciprocal()
}

# See what happens when you pass it malformed na.rm
calc_harmonic_mean(std_and_poor500$pe_ratio, na.rm = 1:5)

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