private string WriteFrequencies(DictionarySlim <long, int> freq, int fragmentLength)
{
var sb = new StringBuilder();
double percent = 100.0 / freq.Select(x => x.Value).Sum();
foreach (var kv in freq.OrderByDescending(i => i.Value))
{
var keyChars = new char[fragmentLength];
var key = kv.Key;
for (int i = keyChars.Length - 1; i >= 0; --i)
{
keyChars[i] = tochar[key & 0x3];
key >>= 2;
}
sb.Append(keyChars);
sb.Append(" ");
sb.AppendLine((kv.Value * percent).ToString("F3"));
}
return(sb.ToString());
}