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Nucleotide Count

Welcome to Nucleotide Count on Exercism's Go Track. If you need help running the tests or submitting your code, check out HELP.md.

Instructions

Each of us inherits from our biological parents a set of chemical instructions known as DNA that influence how our bodies are constructed. All known life depends on DNA!

Note: You do not need to understand anything about nucleotides or DNA to complete this exercise.

DNA is a long chain of other chemicals and the most important are the four nucleotides, adenine, cytosine, guanine and thymine. A single DNA chain can contain billions of these four nucleotides and the order in which they occur is important! We call the order of these nucleotides in a bit of DNA a "DNA sequence".

We represent a DNA sequence as an ordered collection of these four nucleotides and a common way to do that is with a string of characters such as "ATTACG" for a DNA sequence of 6 nucleotides. 'A' for adenine, 'C' for cytosine, 'G' for guanine, and 'T' for thymine.

Given a string representing a DNA sequence, count how many of each nucleotide is present. If the string contains characters that aren't A, C, G, or T then it is invalid and you should signal an error.

For example:

"GATTACA" -> 'A': 3, 'C': 1, 'G': 1, 'T': 2
"INVALID" -> error

Implementation

You should define a custom type 'DNA' with a function 'Counts' that outputs two values:

  • a frequency count for the given DNA strand
  • an error (if there are invalid nucleotides)

Which is a good type for a DNA strand ?

Which is the best Go types to represent the output values ?

Take a look at the test cases to get a hint about what could be the possible inputs.

Note about the tests

You may be wondering about the cases_test.go file. We explain it in the leap exercise.

Source

Created by

  • @kytrinyx

Contributed to by

  • @alebaffa
  • @bitfield
  • @ekingery
  • @ferhatelmas
  • @hilary
  • @ilmanzo
  • @leenipper
  • @mikegehard
  • @petertseng
  • @robphoenix
  • @sebito91
  • @sjakobi
  • @soniakeys
  • @tleen
  • @tompao
  • @eklatzer

Based on

The Calculating DNA Nucleotides_problem at Rosalind - http://rosalind.info/problems/dna/