public void WhenRawEstimateIsSmallerThanAllArrayValuesCorrectBiasIsUsed()
{
// The bias of the first array element should be used
double corrected = BiasCorrection.CorrectBias(10.5, 4);
Assert.Equal(10.5 - 10, corrected);
}
public void WhenRawEstimateIsLargerThanAllArrayValuesCorrectBiasIsUsed()
{
// The bias of the last array element should be used
double corrected = BiasCorrection.CorrectBias(78.0, 4);
Assert.Equal(78.0 - -1.7606, corrected);
}
public void WhenRawEstimateIsBetweenArrayValuesCorrectBiasIsUsed()
{
double corrected = BiasCorrection.CorrectBias(11.1, 4);
// The bias should be between 10 and 9.717, but much closer to 10
Assert.Equal(1.1394700139470011, corrected);
}
public ulong Count()
{
// If only a few elements have been seen, return the exact count
if (this.directCount != null)
{
return (ulong) this.directCount.Count;
}
double zInverse = 0;
double v = 0;
if (this.isSparse)
{
// calc c and Z's inverse
foreach (KeyValuePair<ushort, byte> kvp in this.lookupSparse)
{
byte sigma = kvp.Value;
zInverse += Math.Pow(2, -sigma);
}
v = this.m - this.lookupSparse.Count;
zInverse += (this.m - this.lookupSparse.Count);
}
else
{
// calc c and Z's inverse
for (var i = 0; i < this.m; i++)
{
byte sigma = this.lookupDense[i];
zInverse += Math.Pow(2, -sigma);
if (sigma == 0)
{
v++;
}
}
}
double e = this.alphaM*this.m*this.m/zInverse;
if (e <= 5.0*this.m)
{
e = BiasCorrection.CorrectBias(e, this.bitsPerIndex);
}
double h;
if (v > 0)
{
// LinearCounting estimate
h = this.m*Math.Log(this.m/v);
}
else
{
h = e;
}
if (h <= this.subAlgorithmSelectionThreshold)
{
return (ulong) Math.Round(h);
}
return (ulong) Math.Round(e);
}
public void WhenCorrectedEstimateIsBelowZeroZeroIsReturned()
{
double corrected = BiasCorrection.CorrectBias(5, 4);
Assert.Equal(0, corrected);
}
public void WhenRawEstimateIsInArrayCorrectBiasIsUsed()
{
double corrected = BiasCorrection.CorrectBias(12.207, 4);
Assert.Equal(12.207 - 9.207, corrected);
}
