public DataType SelectRandomItem(RandomSearchQuality quality)
{
if (values.First == null)
{
return(default(DataType)); // no elements
}
if (quality == RandomSearchQuality.Fast)
{
LinkedListNode <DataType> first = values.First;
if (first.Value.Equals(lastSelected))
{
LinkedListNode <double> firstKey = keys.First;
values.RemoveFirst();
keys.RemoveFirst();
values.AddLast(first);
keys.AddLast(firstKey);
first = values.First;
}
lastSelected = first.Value;
return(first.Value);
}
else
{
LinkedListNode <DataType> node = values.First;
for (int chosen = randgen.Next(values.Count); chosen > 0; chosen--)
{
node = node.Next;
}
return(node.Value);
}
}
public DataType SelectSalientItem(RandomSearchQuality quality)
{
if (quality == RandomSearchQuality.Fast)
{
return(SelectSmartItem());
}
else
{
return(SelectExactItem());
}
}
public DataType SelectSalientItem(RandomSearchQuality quality)
{
if (values.First == null)
{
return(default(DataType)); // no elements
}
if (quality == RandomSearchQuality.Fast)
{
LinkedListNode <DataType> first = values.First;
if (first.Value.Equals(lastSelected))
{
// move it to the end
LinkedListNode <double> firstKey = keys.First;
values.RemoveFirst();
keys.RemoveFirst();
values.AddLast(first);
keys.AddLast(firstKey);
first = values.First;
}
lastSelected = first.Value;
return(first.Value);
}
else
{
double target = randgen.NextDouble() * salienceSum;
double sofar = 0;
LinkedListNode <double> nodekey = keys.First;
LinkedListNode <DataType> nodevalue = values.First;
while (nodekey != null && nodevalue != null)
{
sofar += nodekey.Value;
if (sofar >= target)
{
return(nodevalue.Value);
}
nodekey = nodekey.Next;
nodevalue = nodevalue.Next;
}
// Salience calculation failure!
Console.WriteLine("WARNING: Salience miscalculation! Max is " + sofar.ToString() + " not " + salienceSum.ToString());
salienceSum = sofar;
// Try again!
return(SelectSalientItem(quality));
}
}
public DataType SelectRandomItem(RandomSearchQuality quality)
{
if (quality == RandomSearchQuality.Fast)
{
double position;
return(SelectWeightedItem(.5, out position).Data);
}
else
{
int chosen = randgen.Next(Count);
RedBlackEnumerator <double, DataType> enumerator = GetNodeEnumerator();
while (enumerator.HasMoreElements())
{
RedBlackNode <double, DataType> node = enumerator.NextElement();
if (chosen-- == 0)
{
return(node.Data);
}
}
return(default(DataType));
}
}
