Blog of Andrés Aravena

Fixing Errors in the Exam

26 June 2020

People are already working on the exam, and they found some errors in the questions. My mistake, I did not check enough. I apologize.

Error on Question 1.1.

The description talks about a function called baby_rabbits(). You should write that function. But in the answer-1.R file, I wrote it wrong. I just fixed the template file. I recommend that you download it again.

You can see that, in the code to test your answer, we evaluate the function baby_rabbits() for values between 1 and 24, and store the results in a vector called bunnies. Just in case, let me remind you that —according to the dictionary— a bunny is a rabbit, especially a young one.

In summary, in Question 1.1, the function that you should write is called baby_rabbits() and the results are stored in a vector called bunnies.

That is the only error found (so far). If you see something else, please let me know, and I will fix it and tell everybody.

Just for being comprehensive, in Question 1.2, the function is called breeding(), and the results are stored in a data frame called rabbits. In Question 1.3, there is only a data frame, called new_rabbits, which is also used in Question 1.4.

Error on question 2.5

Here the input of gene_cai() function should be called number_of_codons to avoid confusion with the function codon_count(). The question should be this:

Write a function, called gene_cai(), that takes a vector number_of_codons and returns the weighted average of codon_adaptness for each codon.

In other words, you must multiply each component of number_of_codons with the corresponding component of codon_adaptness, sum all the results, and then divide by the sum of all number_of_codons. This answer must be a function.

If you could not calculate codon_adaptness in the previous question, then you can use the values for E.coli, that you can download here.

gene_cai <- function(number_of_codons, codon_adaptness) {
# write your code here

I updated the web version of the exam. Make sure that you are looking at the new version, not the old PDF.

If you have any question, send me an email. Be sure to write to the correct email address.