RosettaCodeData/Task/Entropy/AutoHotkey/entropy.ahk

MsgBox, % Entropy(1223334444)

Entropy(n)
{
    a := [], len := StrLen(n), m := n
    while StrLen(m)
    {
        s := SubStr(m, 1, 1)
        m := RegExReplace(m, s, "", c)
        a[s] := c
    }
    for key, val in a
    {
        m := Log(p := val / len)
        e -= p * m / Log(2)
    }
    return, e
}