Functions writing functions 2 (solution)

Exercise

1. Copy the following function (which converts weights in pounds to weights in grams and rounds them) into your assignment. Replace the ________ with the variable names for the input and output. Replace __ with a number so that by default the function will round the output to one decimal place.

convert_pounds_to_grams <- function(________, numdigits = __) {
  grams <- 453.6 * pounds
  rounded <- round(grams, digits = numdigits)
  return(________)
}

Use the function to calculate how many grams there are in 4.3 pounds using the default for the number of decimal places.

2. Write a function called get_height_from_weight that takes three arguments, weight, a, and b, and returns an estimate of height using height = a * weight ^ b (a prediction from a power model). Give it default arguments of a = 12 and b = 0.38. There should be no default value for weight. Use the default argument values (by passing only the value of weight to the function) to calculate height when weight = 42.

3. Call the function from (2) setting weight to 42, a to 6, and b to 0.5.

4. The function in (2) assumes that the weight is provided in grams. Use the functions from (1) and (2) in combination to estimate the height for an animal that weighs 2 pounds using the default value for a, but changing the value for b to 0.32.

Output solution

Code solution for Writing Functions 2

[1] 1950.5

[1] 49.66106

[1] 38.88444

[1] 106.0831