public void Gini()
{
// arrange
FillItemSet_Features2_Items15();
// act
double gini = _set.GetGini2("F1");
// assert
}
public FeatureNumericalSplitValue Split(ItemNumericalSet set, string resolutionFeatureName)
{
double totalIndex = set.GetGini2(resolutionFeatureName);
if (totalIndex == 0)
{
return(null);
}
double minIndex = totalIndex;
double maxDelta = 0;
int n = set.Count();
var featureNameList = set.GetFeatureNames();
var featureNames = featureNameList.Where(x => x != resolutionFeatureName);
if (!featureNames.Any())
{
throw new Exception();
}
FeatureNumericalSplitValue res = new FeatureNumericalSplitValue();
foreach (string fn in featureNames)
{
set.SortItems(fn);
int qty = set.Count();
for (int k = 1; k < qty; k++)
{
//ItemNumericalSet left = new ItemNumericalSet(featureNameList);
//ItemNumericalSet right = new ItemNumericalSet(featureNameList);
ItemNumericalSet left = set.Clone();
ItemNumericalSet right = set.Clone();
for (int i = 0; i < k; i++)
{
left.AddItem(set.GetItem(i));
}
for (int i = k; i < qty; i++)
{
right.AddItem(set.GetItem(i));
}
double leftIndex = left.GetGini2(resolutionFeatureName);
double rightIndex = right.GetGini2(resolutionFeatureName);
int lc = left.Count();
int rc = right.Count();
double delta = totalIndex - ((lc * 1.0) / n) * leftIndex - ((rc * 1.0) / n) * rightIndex;
if (delta > maxDelta)
{
maxDelta = delta;
res.FeatureName = fn;
double lv = left.GetItem(left.Count() - 1).GetValue(fn);
double rv = right.GetItem(0).GetValue(fn);
res.FeatureValue = Math.Round(lv + (rv - lv) / 2, 5);
res.Left = left;
res.Right = right;
}
}
}
return(res);
}