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How to normalize text to English base

Cand avem o aplicatie care este accesata din mai multe tari, poate sa apara o problema cand se pune problema cautarii sau stocarii datelor. Daca avem o adresa scrisa in limba romana de exemplu o sa avem caractere precum 'â', 'ț', ... dar cand un utilizator dintr-o alta tara o sa caute o anumita adresa de exemplu vrem sa normalizam textul.
O varianta destul de simpla la aceasta problema este sa normalizam tot textul spre caractere ascii base. In acest caz de exemplu 'ț' o sa devina 't'.
Acest lucru se face destul de simplu folosind metoda Normalize, făcând o descompunere canonica a textului.
string normalizeText = sourceText.Normalize(Normalize.FormD);
Trebuie sa avem grija la unele semne de legatura precum 'ß', pentru care trebuie sa facem manual transformarea( dacă dorim).
Mai jos gasiti implementarea pe care eu o propun:
private static readonly char[] SplitChars;
private static readonly Dictionary<char, char> SpecialChars;
static Constructor()
{
SpecialChars = new Dictionary<char, char>();
SpecialChars.Add('ß', 's');

SplitChars = new[] { ' ', '"', '\'', '`', '"', '-', ',', '.' };
}
private string ConvertToBaseASCII(string text)
{
var normalize = text
.ToLowerInvariant()
.Normalize(NormalizationForm.FormD)
.Split(SplitChars, StringSplitOptions.RemoveEmptyEntries);
StringBuilder sb = new StringBuilder();

foreach (string item in normalize)
{
foreach (var c in item)
{
UnicodeCategory unicodeCategory = CharUnicodeInfo.GetUnicodeCategory(c);
if (SpecialChars.Keys.Contains(c))
{
sb.Append(SpecialChars[c]);
continue;
}
if (unicodeCategory != UnicodeCategory.NonSpacingMark)
{
sb.Append(c);
}
}
}

return sb.ToString().Normalize(NormalizationForm.FormC);
}

Comments

  1. Interesant - e foarte buna metoda cat timp user-ul se asteapta sa primeasca ceva mai multe rezultate la o cautare decat la ce se gandea el (search dupa "fata" si obtine "fata", „față”, „fată” sau „făta”).

    Ma tem insa ca metoda merita folosita doar cand trebuie sa iti implementezi singur functia de search, altfel trebuie gasit echivalentul din SQL de ex. (collations si alte cele)

    Cat despre ß (eszett-ul germanilor) din cate am vazut echivalentul e 'ss', nu s, si intr-adevar normalizarea din Unicode nu ajuta aici.. Probabil mai sunt multe cazuri similare in alte limbi, de aia nenea Kaplan nu le trateaza nici el la http://blogs.msdn.com/b/michkap/archive/2007/05/14/2629747.aspx :)

    ReplyDelete
  2. In cazul meu este vorba mai multe de comparare a datelor. Cautarea se face automat de catre un alt sistem si trebuie sa verific daca rezultatul returnat este asemanator cu cea ce a introdus utilizatorul.
    Exista framework-uri care iti permit sa compari doua siruri de caractere si iti pot stabilii cat de asemanatoare sunt cele doua siruri, dar eu nu aveam nevoie de un mecanism atat de complex.

    ReplyDelete

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