public static DecisionTreeScore ScoreWithTreeWithTestSet(DecisionTreeLevel decisionTree, List <DataSetValue> testDataSetValues)
{
return(ScoreWithTreeWithTestSet(new List <DecisionTreeLevel>()
{
decisionTree
}, testDataSetValues));
}
public void D3()
{
// Check whether we even need to split or not
int totalTrueValues = _values.Count(v => v.Output);
int totalFalseValues = _values.Count(v => !v.Output);
if (totalFalseValues == 0 && totalTrueValues > 0)
{
_localValue = true;
return;
}
if (totalTrueValues == 0 && totalFalseValues > 0)
{
_localValue = false;
return;
}
// Can we split on attributes?
if (_attributes.Count == 0)
{
// Can't split anymore. We'll decide on the most prevalent value
_localValue = totalTrueValues > totalFalseValues;
return;
}
// First, find the attribute with the highest "E"
List <DataSetAttributeWithCounts> e = CalculateEForAllAttributes(_attributes, _values);
DataSetAttributeWithCounts attributeWithMinEntropy = FindAttributeWithMinEntropy(e);
_attributeToSplitOn = attributeWithMinEntropy;
// Is it worth it to split on attributes
if (!ShouldSplitOnAttributeAccordingToChiSquared(attributeWithMinEntropy))
{
// Not worth it to split. We'll decide on the most prevalent value
_localValue = totalTrueValues > totalFalseValues;
return;
}
// Remove this attribute from the list of new attributes to create new subtrees
List <DataSetAttribute> newAttributes = _attributes.Where(a => a.Name != attributeWithMinEntropy.Name).ToList();
// Split the values in many sets
_dictionaryOfSubTrees = new Dictionary <string, DecisionTreeLevel>(attributeWithMinEntropy.PossibleValues.Count);
var dictionaryOfValues = new Dictionary <string, List <DataSetValue> >();
foreach (var dataSetValue in _values)
{
string value = dataSetValue.Values[attributeWithMinEntropy.ValueIndex];
DecisionTreeLevel localTreeLevel;
List <DataSetValue> localValues;
if (!_dictionaryOfSubTrees.TryGetValue(value, out localTreeLevel))
{
localValues = new List <DataSetValue>();
dictionaryOfValues[value] = localValues;
localTreeLevel = new DecisionTreeLevel(ChiTestLimit, newAttributes, localValues);
_dictionaryOfSubTrees[value] = localTreeLevel;
}
else
{
localValues = dictionaryOfValues[value];
}
localValues.Add(dataSetValue);
}
// Recursively run D3 on them
foreach (var decisionTree in _dictionaryOfSubTrees)
{
List <DataSetValue> localValues = dictionaryOfValues[decisionTree.Key];
decisionTree.Value.D3();
}
}
