C-Sharp/Algorithms/Encoders/SoundexEncoder.cs at master · TheAlgorithms/C-Sharp · GitHub

Name: C-Sharp/Algorithms/Encoders/SoundexEncoder.cs at master · TheAlgorithms/C-Sharp · GitHub
Rating: 4.8 (1817 reviews)
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usingSystem.Collections.Generic;
usingSystem.Linq;

namespaceAlgorithms.Encoders;

/// <summary>
/// Class for Soundex encoding strings.
/// </summary>
publicclassSoundexEncoder
{
/// <summary>
/// Encodes a string using the Soundex Algorithm.
/// </summary>
/// <param name="text">The string to encode.</param>
/// <returns>The Soundex encoded string (one uppercase character and three digits).</returns>
publicstringEncode(stringtext)
{
text=text.ToLowerInvariant();
varchars=OmitHAndW(text);
IEnumerable<int>numbers=ProduceNumberCoding(chars);
numbers=CollapseDoubles(numbers);
numbers=OmitVowels(numbers);
numbers=CollapseLeadingDigit(numbers,text[0]);
numbers=numbers.Take(3);
numbers=PadTo3Numbers(numbers);
varfinal=numbers.ToArray();
return$"{text.ToUpperInvariant()[0]}{final[0]}{final[1]}{final[2]}";
}

privateIEnumerable<int>CollapseLeadingDigit(IEnumerable<int>numbers,charc)
{
usingvarenumerator=numbers.GetEnumerator();
enumerator.MoveNext();
if(enumerator.Current==MapToNumber(c))
{
enumerator.MoveNext();
}

do
{
yieldreturnenumerator.Current;
}
while(enumerator.MoveNext());
}

privateIEnumerable<int>PadTo3Numbers(IEnumerable<int>numbers)
{
usingvarenumerator=numbers.GetEnumerator();
for(vari=0;i<3;i++)
{
yieldreturnenumerator.MoveNext()
?enumerator.Current
:0;
}
}

privateIEnumerable<int>OmitVowels(IEnumerable<int>numbers)=>numbers.Where(i =>i!=0);

privateIEnumerable<char>OmitHAndW(stringtext)=>text.Where(c =>c!='h'&&c!='w');

privateIEnumerable<int>CollapseDoubles(IEnumerable<int>numbers)
{
varprevious=int.MinValue;
foreach(variinnumbers)
{
if(previous!=i)
{
yieldreturni;
previous=i;
}
}
}

privateIEnumerable<int>ProduceNumberCoding(IEnumerable<char>text)=>text.Select(MapToNumber);

privateintMapToNumber(charch)
{
varmapping=newDictionary<char,int>
{
['a']=0,
['e']=0,
['i']=0,
['o']=0,
['u']=0,
['y']=0,
['h']=8,
['w']=8,
['b']=1,
['f']=1,
['p']=1,
['v']=1,
['c']=2,
['g']=2,
['j']=2,
['k']=2,
['q']=2,
['s']=2,
['x']=2,
['z']=2,
['d']=3,
['t']=3,
['l']=4,
['m']=5,
['n']=5,
['r']=6,
};

returnmapping[ch];
}
}