25. Normalización y Preprocesamiento de Datos para IA

public class TextNormalizer
{
    public string Normalize(string text)
    {
        if (string.IsNullOrWhiteSpace(text))
            return string.Empty;

        // 1. Lowercase
        text = text.ToLowerInvariant();

        // 2. Remover acentos
        text = RemoveAccents(text);

        // 3. Remover caracteres especiales
        text = RemoveSpecialCharacters(text);

        // 4. Normalizar espacios
        text = NormalizeWhitespace(text);

        return text.Trim();
    }

    private string RemoveAccents(string text)
    {
        var normalizedString = text.Normalize(NormalizationForm.FormD);
        var stringBuilder = new StringBuilder();

        foreach (var c in normalizedString)
        {
            var unicodeCategory = CharUnicodeInfo.GetUnicodeCategory(c);
            if (unicodeCategory != UnicodeCategory.NonSpacingMark)
            {
                stringBuilder.Append(c);
            }
        }

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

public class Tokenizer
{
    private readonly HashSet<string> _stopWords = new()
    {
        "el", "la", "de", "que", "y", "a", "en", "un", "ser", "se", "no"
    };

    public List<string> Tokenize(string text, bool removeStopWords = true)
    {
        var tokens = text
            .Split(new[] { ' ', '\t', '\n', '\r', ',', '.', ';', ':', '!', '?' },
                StringSplitOptions.RemoveEmptyEntries)
            .Select(t => t.ToLowerInvariant())
            .Where(t => t.Length > 2);

        if (removeStopWords)
        {
            tokens = tokens.Where(t => !_stopWords.Contains(t));
        }

        return tokens.ToList();
    }
}

public class DataCleaner
{
    public string CleanBusinessHours(string hours)
    {
        // Normalizar horarios de negocio
        // "Lunes a Viernes: 9-14h" → "L-V: 09:00-14:00"
        return hours;
    }

    public string CleanPhoneNumber(string phone)
    {
        // Normalizar números de teléfono
        // "+34 666 123 456" → "666123456"
        return Regex.Replace(phone, @"[^\d]", "");
    }
}