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  3. String Manipulation with stringr in R

Exercise

Review

You've covered a lot of stringr functions in this chapter:

  • str_c()
  • str_length()
  • str_sub()
  • str_detect()
  • str_subset()
  • str_count()
  • str_split()
  • str_replace()

As a review we've got a few tasks for you to do with some DNA sequences. We've put three sequences, corresponding to three genes, from the genome of Yersinia pestis – the bacteria that causes bubonic plague – into the vector genes.

Each string represents a gene, each character a particular nucleotide: Adenine, Cytosine, Guanine or Thymine.

We aren't going to tell you which function to use. It's up to you to choose the right one and specify the needed arguments. Good luck!

Instructions

100 XP
  • Find the number of nucleotides in each gene.
  • Find the number of A's that occur in each gene.
  • Return the sequences that contain the sequence "TTTTTT".
  • Replace all the As in the sequences with a _.