EntropyGeneric.cs

Detect Entropy Levels from Primitive Data Arrays

using System;
using System.Collections.Generic;
public class EntropyGeneric<T>
{
    private const    double             NaturalLogOfTwo = 0.69314718055994530941723212145818;
    private readonly Dictionary<T, int> _hist           = new Dictionary<T, int>();
    private          bool               _mapStatus;
    public EntropyGeneric()
    {
        _hist.Clear();
        _mapStatus = false;
    }
    public (double entropy, int perfect) Entropy(T[] s)
    {
        if (_mapStatus)
        {
            _hist.Clear();
            _mapStatus = false;
        }
        foreach (var c in s)
            if (!_hist.ContainsKey(c))
                _hist.Add(c, 1);
            else
                _hist[c] += 1;
        _mapStatus = true;
        var e = 0.0;
        foreach (var v in _hist.Values)
        {
            if (v <= 0)
                continue;
            var r = v             / (double) s.Length;
            e -= r * (Math.Log(r) / NaturalLogOfTwo);
        }
        return (e, GetSize());
    }
    private byte[] ConvertTypeByteArray(T[] ia)
    {
        switch (Type.GetTypeCode(typeof(T)))
        {
            case TypeCode.Boolean:
                break;
            case TypeCode.Char:
                break;
            case TypeCode.SByte:
                break;
            case TypeCode.Byte:
                break;
            case TypeCode.Int16:
                break;
            case TypeCode.UInt16:
                break;
            case TypeCode.Int32:
                break;
            case TypeCode.UInt32:
                break;
            case TypeCode.Single:
                break;
            case TypeCode.String:
                break;
            case TypeCode.Decimal:
                break;
            case TypeCode.Int64:
                break;
            case TypeCode.UInt64:
                break;
            case TypeCode.Double:
                break;
            case TypeCode.DateTime:
                break;
            default:
                throw new ArgumentException("Type is not a valid primitive.");
        }
        return ia.GetBytesObject();
    }
    private int GetSize()
    {
        var size = 0;
        switch (Type.GetTypeCode(typeof(T)))
        {
            case TypeCode.Boolean:
                size = 8;
                break;
            case TypeCode.Char:
                size = 16;
                break;
            case TypeCode.SByte:
                size = 8;
                break;
            case TypeCode.Byte:
                size = 8;
                break;
            case TypeCode.Int16:
                size = 16;
                break;
            case TypeCode.UInt16:
                size = 16;
                break;
            case TypeCode.Int32:
                size = 32;
                break;
            case TypeCode.UInt32:
                size = 32;
                break;
            case TypeCode.Single:
                size = 32;
                break;
            case TypeCode.String:
                size = 32;
                break;
            case TypeCode.Decimal:
                size = 96;
                break;
            case TypeCode.Int64:
                size = 64;
                break;
            case TypeCode.UInt64:
                size = 64;
                break;
            case TypeCode.Double:
                size = 64;
                break;
            case TypeCode.DateTime:
                size = 64;
                break;
            default:
                throw new ArgumentException("Type is not a valid primitive.");
        }
        return size;
    }
}