Substring with Dictionary

Protein Translation
Protein Translation in C# 
using System;
using System.Collections.Generic;

public static class ProteinTranslation
{
    private static readonly Dictionary<string, string> lookup = new Dictionary<string, string>();

    private static void roboLoad(string protein, params string[] codons)
    {
        foreach (string codon in codons)
            lookup.Add(codon, protein);
    }

    static ProteinTranslation()
    {
        roboLoad("Methionine", "AUG");
        roboLoad("Phenylalanine", "UUU", "UUC");
        roboLoad("Leucine", "UUA", "UUG");
        roboLoad("Serine", "UCU", "UCC", "UCA", "UCG");
        roboLoad("Tyrosine", "UAU", "UAC");
        roboLoad("Cysteine", "UGU", "UGC");
        roboLoad("Tryptophan", "UGG");
        roboLoad("STOP", "UAA", "UAG", "UGA");
    }

    public static string[] Proteins(string strand)
    {
        var length = strand.Length;
        List<String> proteins = new List<String>();
        var endIndex = 3;
        while (endIndex <= length)
        {
            var codon = strand.Substring(endIndex - 3, 3);
            var protein = lookup[codon];
            switch (protein)
            {
                case "STOP":
                    return proteins.ToArray();
                default:
                    proteins.Add(protein);
                    break;
            }
            endIndex += 3;
        }
        return proteins.ToArray();
    }
}

The approach begins by defining a private, static, readonly Dictionary for translating the codons to proteins. It is private because it isn't needed outside the class. It is static because only one is needed to serve every instance of the class. It is readonly because, although it has interior mutability (meaning its elements can change), the Dictionary variable itself will not be assigned to another Dictionary.

A private static helper method is defined to load the Dictionary from the supplied protein and its matching codon(s).

The static constructor calls the helper method with the necessary arguments.

The Proteins() method starts by defining a List and a couple of variables to control iterating the codons.

While there are still characters left to iterate, a codon is set from a Substring() of the input strand. The matching protein for the codon is looked up from the Dictionary and is tested in a switch. If the codon was a STOP codon, then break is used to exit the loop. If not, then the protein is added to the List.

After the loop is finished, the List's ToArray() method is used to return an array of the matched proteins from the method.

11th Dec 2024 · Found it useful?

Other Approaches to Protein Translation in C#

Other ways our community solved this exercise
while (endIndex <= length)
{
    var codon = strand.Substring(endIndex - 3, 3);
    var protein = ToProtein(codon);
    switch (protein)
    {
        case "STOP":
            return proteins.ToArray();
Switch on a tuple

Iterate Substrings with switch. 

return strand
    .Select((_, i) => i)
    .Where(i => i % 3 == 0)
    .Select(i =>  proteins[strand.Substring(i, 3)])
    .TakeWhile(protein => protein != "STOP")
    .ToArray();
LINQ with Dictionary

Use LINQ with Dictionary. 

public static string[] Proteins(string strand) =>
    strand.Chunked(3).Select(codon => proteins[codon]).TakeWhile(protein => protein != "STOP").ToArray();

private static IEnumerable<string> Chunked(this string input, int size)
{
    for (var i = 0; i < input.Length; i += size)
        yield return input[i..(i + size)];
}
yield with Dictionary

Iterate using yield with Dictionary. 

public static string[] Proteins(string strand) =>
   strand.Chunked(3).Select(ToProtein).TakeWhile(protein => protein != "STOP").ToArray();

private static IEnumerable<string> Chunked(this string input, int size)
{
    for (var i = 0; i < input.Length; i += size)
        yield return input[i .. (i + size)];
}
yield with switch

Iterate using yield with switch.