public ProxyCountTable(int iCol, int iSlot, ICountTable baseCountTable)
{
Contracts.CheckValue(baseCountTable, nameof(baseCountTable));
Contracts.Check(baseCountTable.GarbageThreshold == 0, "Garbage bin not supported for shared table");
_mixin = Hashing.MurmurRound((uint)iCol, (uint)iSlot);
_table = baseCountTable;
}
// Fills _labelBinCount log odds features. One per class, or only one if 2 classes.
private void GenerateLogOdds(int iCol, ICountTable countTable, Span <float> counts, Span <float> logOdds, float sum)
{
_host.Assert(counts.Length == _labelBinCount);
_host.Assert(logOdds.Length == _logOddsCount);
for (int i = 0; i < _logOddsCount; i++)
{
_host.Assert(counts[i] >= 0);
if (counts[i] <= 0 && countTable.PriorFrequencies[i] <= 0 || countTable.PriorFrequencies[i] >= 1)
{
logOdds[i] = 0; // guarding against infinite log-odds
}
else
{
logOdds[i] = (float)Math.Log(
(counts[i] + PriorCoef[iCol] * countTable.PriorFrequencies[i]) /
(sum - counts[i] + PriorCoef[iCol] * (1 - countTable.PriorFrequencies[i])));
}
}
}
