public long GetCurrentValue(IChannel ch, long count, long valMax)
{
// Note: This method should not modify any fields.
AssertValid(valMax);
Contracts.Assert(count >= _cna);
// If the sum is zero, return zero.
if ((_sumHi | _sumLo) == 0)
{
// If all values in a given column are NAs issue a warning.
if (count == _cna)
{
ch.Warning("All values in this column are NAs, using default value for imputation");
}
return(0);
}
Contracts.Assert(count > _cna);
count -= _cna;
Contracts.Assert(count > 0);
ulong sumHi = _sumHi;
ulong sumLo = _sumLo;
bool neg = (long)sumHi < 0;
if (neg)
{
// Negative value. Work with the absolute value.
sumHi = ~sumHi;
sumLo = ~sumLo;
IntUtils.Add(ref sumHi, ref sumLo, 1);
}
// If this assert triggers, the caller did something wrong. Update should have been
// called at most count times and each value should have been within the range of
// a ulong, so the absolute value of the sum can't possibly be so large that sumHi
// reaches or exceeds count. This assert implies that the Div part of the DivRound
// call won't throw.
Contracts.Assert(sumHi < (ulong)count);
ulong res = IntUtils.DivRound(sumLo, sumHi, (ulong)count);
Contracts.Assert(0 <= res && res <= (ulong)valMax);
return(neg ? -(long)res : (long)res);
}
