Given a DNA strand, return its RNA complement (per RNA transcription).
Both DNA and RNA strands are a sequence of nucleotides.
The four nucleotides found in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T).
The four nucleotides found in RNA are adenine (A), cytosine (C), guanine (G) and uracil (U).
Given a DNA strand, its transcribed RNA strand is formed by replacing each nucleotide with its complement:
G
-> C
C
-> G
T
-> A
A
-> U
Execute the tests with:
$ elixir rna_transcription_test.exs
In the test suites, all but the first test have been skipped.
Once you get a test passing, you can unskip the next one by
commenting out the relevant @tag :pending
with a #
symbol.
For example:
# @tag :pending
test "shouting" do
assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
end
Or, you can enable all the tests by commenting out the
ExUnit.configure
line in the test suite.
# ExUnit.configure exclude: :pending, trace: true
If you're stuck on something, it may help to look at some of the available resources out there where answers might be found.
Hyperphysics http://hyperphysics.phy-astr.gsu.edu/hbase/Organic/transcription.html
It's possible to submit an incomplete solution so you can see how others have completed the exercise.
if !System.get_env("EXERCISM_TEST_EXAMPLES") do
Code.load_file("rna_transcription.exs", __DIR__)
end
ExUnit.start()
ExUnit.configure(exclude: :pending, trace: true)
defmodule RNATranscriptionTest do
use ExUnit.Case
# @tag :pending
test "transcribes guanine to cytosine" do
assert RNATranscription.to_rna('G') == 'C'
end
@tag :pending
test "transcribes cytosine to guanine" do
assert RNATranscription.to_rna('C') == 'G'
end
@tag :pending
test "transcribes thymidine to adenine" do
assert RNATranscription.to_rna('T') == 'A'
end
@tag :pending
test "transcribes adenine to uracil" do
assert RNATranscription.to_rna('A') == 'U'
end
@tag :pending
test "it transcribes all dna nucleotides to rna equivalents" do
assert RNATranscription.to_rna('ACGTGGTCTTAA') == 'UGCACCAGAAUU'
end
end
defmodule RNATranscription do
@dna_nucleotide_to_rna_nucleotide_map %{
# `G` -> `C`
71 => 67,
# `C` -> `G`
67 => 71,
# `T` -> `A`
84 => 65,
# `A` -> `U`
65 => 85
}
@doc """
Transcribes a character list representing DNA nucleotides to RNA
## Examples
iex> RNATranscription.to_rna('ACTG')
'UGAC'
"""
@spec to_rna([char]) :: [char]
def to_rna(dna) do
dna
|> Enum.map(&get_rna_for_dna/1)
end
defp get_rna_for_dna(dna_nucleotide) do
@dna_nucleotide_to_rna_nucleotide_map[dna_nucleotide]
end
end
A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.
Here are some questions to help you reflect on this solution and learn the most from it.
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