MET581 Lecture 05 Homework

Wrangling Data 3

Author

Matthew Bracher-Smith

Published

October 21, 2024

This document contains all questions for the lecture ‘Wrangling Data 3’. Please create a Quarto document containing all text, code and output used to answer the questions.

1 Factors

  1. When does fct_lump() stop adding levels into “other”?

  2. Load the gss_cat dataframe and get a summary to see if the amount of tv hours per day affects the political party a person belongs to.

  3. Repeat the previous exercise, but this time merge all the “other party” levels into a single option and reorder the factor by the average tv hours per day.

You have a vector of categorical data that has a natural order to it, and you want to use in a regression model. The vector is c(‘Some’, ‘All’, ‘None’, ‘Half’, ‘Most’, ‘Most’, ‘Most’, ‘All’, ‘Some’, ‘None’). Create a factor from this vector by pasting it into the factor() function and assign to a variable.

  1. You’re concerned to make sure that ‘None’ is set as the baseline. Check the coding for regression problems with contrasts() and print the output.

  2. Why are the levels in this order by default?

  3. Re-order the levels of this factor to go from ‘None’ to ‘All’ in increasing amount

2 Functions

  1. Can you tell which of the arguments of myFunction are mandatory and which are optional?
myFunction <- function(x, y, verbose = FALSE){
  result <- x ** y
  if (verbose){
    print(result)
  }
  return(result)
}

  1. What will be the output of the previous function if we type the following command myFunction(2, 3, TRUE)? Try to do it without running the code.

  2. Write any_na(), a function that takes two vectors of the same length and returns the number of positions that have an NA in, at least, one of the vectors.

  3. Write complementary(), a function that takes a DNA strand of variable length and returns its complementary strand.

  4. Write a function that transcribes and translates a DNA strand into its corresponding protein sequence. You can assume that the length of the input DNA strand is a multiple of 3.