Foldable operations (I)

An operation that gives the same answer whether you apply it to an entire data set or to chunks of a data set and then on the results on the chunks is sometimes called foldable. The max() and min() operations are an example of this. Here, we have defined a foldable version of the range() function that takes either a vector or list of vectors. Verify that the function works by testing it on the mortgage data set.

This exercise is part of the course

Scalable Data Processing in R

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Exercise instructions

Verify that foldable_range() works on the "record_number" column of the mort data set.

Hands-on interactive exercise

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

foldable_range <- function(x) {
  if (is.list(x)) {
    # If x is a list then reduce it by the min and max of each element in the list
    c(Reduce(min, x), Reduce(max, x))
  } else {
    # Otherwise, assume it's a vector and find its range
    range(x)
  }
}

# Verify that foldable_range() works on the record_number column
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