/// <summary>
/// Splits data into Tuples and builds a Decision Tree
/// </summary>
/// <param name="inputLines"></param>
/// <param name="attributeArray"></param>
/// <param name="attributeNames"></param>
/// <param name="continuousAttributeNames"></param>
/// <param name="continuousAttributeValues"></param>
/// <param name="continousIndexes"></param>
/// <param name="userLabels"></param>
/// <returns></returns>
public static Tree BuildTree(string[] inputLines, List <Attribute> attributeArray, string[] attributeNames, List <string> continuousAttributeNames,
Dictionary <string, List <double> > continuousAttributeValues, List <int> continousIndexes, Attribute userLabels)
{
List <Tuple> tuples = new List <Tuple>();
//build the continuous attributes
List <double>[] continuousVals = new List <double> [continuousAttributeNames.Count];
for (int i = 0; i < continuousVals.Length; ++i)
{
continuousVals[i] = new List <double>();
}
for (int i = 0; i < inputLines.Length - attributeArray.Count - 2; ++i)
{
string[] tupleInfo = inputLines[i + 2 + attributeArray.Count].Split(' ', StringSplitOptions.RemoveEmptyEntries);
string[] tupleAttributes = new string[tupleInfo.Length - 1];
Array.Copy(tupleInfo, 0, tupleAttributes, 0, tupleAttributes.Length);
tuples.Add(new Tuple(tupleInfo[tupleInfo.Length - 1], attributeNames, tupleAttributes));
int continuousCount = 0;
for (int j = 0; j < tupleAttributes.Length; ++j)
{
if (continousIndexes.Contains(j))
{
continuousVals[continuousCount].Add(Convert.ToDouble(tupleAttributes[j]));
++continuousCount;
}
}
}
for (int i = 0; i < continuousAttributeNames.Count; i++)
{
continuousAttributeValues.Add(continuousAttributeNames[i], continuousVals[i]);
continuousAttributeValues[continuousAttributeNames[i]].Sort();
}
foreach (string contName in continuousAttributeNames)
{
double split;
split = (continuousAttributeValues[contName][0] + continuousAttributeValues[contName][1]) / 2;
double minExpectInfo = Double.MaxValue;
for (int i = 0; i < tuples.Count - 1; ++i)
{
double splitPoint = (continuousAttributeValues[contName][0] + continuousAttributeValues[contName][i + 1]) / 2;
List <Tuple>[] subList = new List <Tuple> [2];
for (int j = 0; j < subList.Length; ++j)
{
subList[j] = new List <Tuple>();
}
foreach (Tuple tuple in tuples)
{
if (Convert.ToDouble(tuple.AttributeValues[contName]) <= splitPoint)
{
subList[0].Add(tuple);
}
else
{
subList[1].Add(tuple);
}
}
double expectedInfo = Equations.ExpectedInfoWithPartition(tuples, subList, userLabels);
if (expectedInfo < minExpectInfo)
{
minExpectInfo = expectedInfo;
split = splitPoint;
}
}
for (int i = 0; i < tuples.Count; ++i)
{
if (split != 0)
{
if (Convert.ToDouble(tuples[i].AttributeValues[contName]) <= split)
{
tuples[i].AttributeValues[contName] = " <= " + split.ToString("F1");
}
else
{
tuples[i].AttributeValues[contName] = " > " + split.ToString("F1");
}
}
else
{
if (Convert.ToDouble(tuples[i].AttributeValues[contName]) <= split)
{
Convert.ToInt32(split);
tuples[i].AttributeValues[contName] = " <= " + split.ToString();
}
else
{
Convert.ToInt32(split);
tuples[i].AttributeValues[contName] = " > " + split.ToString();
}
}
}
int contAttributeIndex = -1;
for (int i = 0; i < attributeArray.Count; ++i)
{
if (attributeArray[i].AttributeName == contName)
{
contAttributeIndex = i;
break;
}
}
attributeArray[contAttributeIndex].Values = new string[2];
if (split != 0)
{
attributeArray[contAttributeIndex].Values[0] = " <= " + split.ToString("F1");
attributeArray[contAttributeIndex].Values[1] = " > " + split.ToString("F1");
}
else //split = 0 so no need for the extra decimal place -> 0.0
{
attributeArray[contAttributeIndex].Values[0] = " <= " + split.ToString();
attributeArray[contAttributeIndex].Values[1] = " > " + split.ToString();
}
}
//build the tree
Tree decisionTree = new Tree(string.Empty, string.Empty);
decisionTree.TreeRecursion(tuples, decisionTree.Root, attributeArray, userLabels, continuousAttributeNames);
return(decisionTree);
}
//Member Functions
//recursively build the tree by splitting on a particular attribute, based on information gain
public void TreeRecursion(List <Tuple> tupleArray, TreeNode parentNode, List <Attribute> attributeArray, Attribute userLabels, List <string> continuousAttributeNames, TreeNode prevNode = null, int childIndex = -1)
{
if (tupleArray.Count > 0 && attributeArray.Count > 0 && !Equations.SubListClassesAreSame(tupleArray))
{
string bestAttribute = string.Empty;
double minExpectInfo = double.MaxValue;
foreach (Attribute attribute in attributeArray)
{
Dictionary <string, List <Tuple> > attrSubLists = new Dictionary <string, List <Tuple> >();
foreach (string value in attribute.Values)
{
attrSubLists.Add(value, new List <Tuple>());
}
foreach (Tuple t in tupleArray)
{
attrSubLists[t.AttributeValues[attribute.AttributeName]].Add(t);
}
List <Tuple>[] attrSubListArray = new List <Tuple> [attrSubLists.Count];
for (int i = 0; i < attrSubLists.Count; ++i)
{
attrSubListArray[i] = attrSubLists[attribute.Values[i]];
}
double expectedInfo = Equations.ExpectedInfoWithPartition(tupleArray, attrSubListArray, userLabels);
if (expectedInfo < minExpectInfo)
{
minExpectInfo = expectedInfo;
bestAttribute = attribute.AttributeName;
}
}
parentNode.NextAttribute = bestAttribute;
Dictionary <string, List <Tuple> > subLists = new Dictionary <string, List <Tuple> >();
int bestAttributeIndex = -1;
for (int i = 0; i < attributeArray.Count; ++i)
{
if (attributeArray[i].AttributeName == bestAttribute)
{
bestAttributeIndex = i;
break;
}
}
foreach (string value in attributeArray[bestAttributeIndex].Values)
{
subLists.Add(value, new List <Tuple>());
}
foreach (Tuple t in tupleArray)
{
subLists[t.AttributeValues[attributeArray[bestAttributeIndex].AttributeName]].Add(t);
}
List <Tuple>[] subListArray = new List <Tuple> [subLists.Count];
for (int i = 0; i < subLists.Count; ++i)
{
subListArray[i] = subLists[attributeArray[bestAttributeIndex].Values[i]];
}
List <Attribute> prunedAttributeArray = new List <Attribute>(attributeArray);
prunedAttributeArray.RemoveAt(bestAttributeIndex);
//for (int i = 0; i < subListArray.Length; ++i)
int index = 0;
int iteration = 0;
while (iteration < subListArray.Length)
{
if (continuousAttributeNames.Contains(bestAttribute))
{
parentNode.AddChild(attributeArray[bestAttributeIndex].Values[iteration] + ":", string.Empty);
}
else
{
parentNode.AddChild("=" + attributeArray[bestAttributeIndex].Values[iteration] + ":", string.Empty);
}
TreeRecursion(subListArray[iteration], parentNode.Children[index], prunedAttributeArray, userLabels, continuousAttributeNames, parentNode, index);
if (pruned_status)
{
parentNode.Children.RemoveAt(index);
pruned_status = false;
index = 0;
iteration++;
continue;
}
iteration++;
index++;
}
}
else if (tupleArray.Count > 0 && attributeArray.Count == 0)
{
Dictionary <string, int> classCount = new Dictionary <string, int>();
foreach (string tupleClass in userLabels.Values)
{
classCount.Add(tupleClass, 0);
}
foreach (Tuple tuple in tupleArray)
{
++classCount[tuple.Class];
}
int maxFrequency = int.MinValue;
string modeClass = string.Empty;
foreach (string tupleClass in userLabels.Values)
{
if (classCount[tupleClass] > maxFrequency)
{
maxFrequency = classCount[tupleClass];
modeClass = tupleClass;
}
}
parentNode.NextAttribute = modeClass;
}
else if (tupleArray.Count == 0) //no tuples left left to branch off of
{
if (childIndex != -1) //prune the child
{
pruned_status = true;
}
else
{
parentNode.NextAttribute = "No data left";
}
}
else //all the tuples are of the same class
{
parentNode.NextAttribute = tupleArray[0].Class;
}
}
