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JaeHyoLee's solution

to Nucleotide Count in the Lua Track

Published at Jul 13 2018 · 0 comments
Test suite

Given a single stranded DNA string, compute how many times each nucleotide occurs in the string.

The genetic language of every living thing on the planet is DNA. DNA is a large molecule that is built from an extremely long sequence of individual elements called nucleotides. 4 types exist in DNA and these differ only slightly and can be represented as the following symbols: 'A' for adenine, 'C' for cytosine, 'G' for guanine, and 'T' thymine.

Here is an analogy:

  • twigs are to birds nests as
  • nucleotides are to DNA as
  • legos are to lego houses as
  • words are to sentences as...

Running the tests

To run the tests, run the command busted from within the exercise directory.

Further information

For more detailed information about the Lua track, including how to get help if you're having trouble, please visit the exercism.io Lua language page.


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

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.


local DNA = require('nucleotide-count')

describe('nucleotide-count', function()
  it('has no nucleotides', function()
    local expected =  { A = 0, T = 0, C = 0, G = 0 }
    dna = DNA:new('')
    local result = dna.nucleotideCounts
    assert.are.same(expected, result)

  it('has no adenosine', function()
    local dna = DNA:new('')
    local expected = 0
    result = dna:count('A')
    assert.are.same(expected, result)

  it('repetitive cytosine gets counts', function()
    local dna = DNA:new('CCCCC')
    local expected = 5
    result = dna:count('C')
    assert.are.same(expected, result)

  it('repetitive sequence has only guanosine', function()
    local dna = DNA:new('GGGGGGGG')
    expected = { A = 0, T = 0, C = 0, G = 8 }
    result = dna.nucleotideCounts
    assert.are.same(expected, result)

  it('counts only thymine', function()
    local dna = DNA:new('GGGGTAACCCGG')
    expected = 1
    result = dna:count('T')
    assert.are.same(expected, result)

  it('counts a nucleotide only once', function()
    local dna = DNA:new('GGTTGG')
    expected = 2
    result = dna:count('T')
    assert.are.same(expected, result)

  it('validates nucleotides', function()
    local dna = DNA:new('GGTTGG')
     assert.has.errors(function() dna:count('X') end)
     assert.has_error(function() dna:count('X') end, 'Invalid Nucleotide')

  it('counts all nucleotides', function()
    expected = { A = 20, T = 21, G = 17, C = 12 }
    result = dna.nucleotideCounts
    assert.are.same(expected, result)
local n_count = {}

function n_count:count(base)
  assert(self.nucleotideCounts[base], 'Invalid Nucleotide')
  return self.nucleotideCounts[base]

function n_count:new(dna)
  local o = {}
  setmetatable(o, self)
  self.__index = self

  o.nucleotideCounts = { A = 0, T = 0, C = 0, G = 0 }

  for i = 1, #dna do
    local c = dna:sub(i,i)
    assert(o.nucleotideCounts[c], 'Invalid Nucleotide')
    o.nucleotideCounts[c] = o.nucleotideCounts[c] + 1
  return o

return n_count

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