public override void Copy(DDSketchStore store_)
{
Contract.Requires(store_ is DDSketchUnboundedStore);
var store = (DDSketchUnboundedStore)store_;
_data = new Dictionary <int, int>(store._data);
}
public override void Merge(DDSketchStore store_)
{
Contract.Requires(store_ is DDSketchUnboundedStore);
var store = (DDSketchUnboundedStore)store_;
foreach (var kvp in store._data)
{
if (!_data.ContainsKey(kvp.Key))
{
_data[kvp.Key] = kvp.Value;
}
else
{
_data[kvp.Key] += kvp.Value;
}
}
}
public DDSketch(double alpha = 0.01, double minimumRepresentableValue = 1e-9, DDSketchStore?store = null)
{
Contract.Requires(0 < alpha && alpha < 1, "Alpha must be a probability");
Contract.Requires(minimumRepresentableValue >= 0, "The minimum absolute value must be at least 0");
Alpha = alpha;
_minimumRepresentableValue = minimumRepresentableValue;
Gamma = 1.0 + ((2.0 * Alpha) / (1.0 - Alpha));
Contract.Assert(Gamma >= 1.0);
// \gamma = 1 + \frac{2 \alpha}{1 - \alpha}, so this is exactly \ln \gamma
_ln_gamma = Log1p((2.0 * Alpha) / (1.0 - Alpha));
_minimumRepresentableOffset = -ObliviousIndex(_minimumRepresentableValue) + 1;
Contract.Assert(_minimumRepresentableOffset > 0);
_store = store ?? new DDSketchUnboundedStore();
}