Functions

String Data

This is a follow up to Strings from Data.

A colleague has produced a file with one DNA sequence on each line. Download the file and load it into R using read.csv(). The file has no header.

Write a function to calculate GC content. GC content is the percentage of bases that are either G or C as a percentage of total base pairs. Your function should take a dna sequence as input and return the GC-content of that sequence. Print the result for each sequence.

Before we knew about functions we had to take each dna sequence one at a time and then rewrite or copy-paste the same code to analyze each one. Isn’t this better?

You may have noticed that for Loop prints the results differently. read.csv() imports the data as a data.frame(), unlike the numeric vector in the previous exercise.

[click here for output]