public ConditionalTree BuildConditionalTree()
{
var listRows = new List<int>();
for (int index = 0; index < _data.Count; index++)
{
listRows.Add(index);
}
if (listRows.Count == 0)
{
return null;
}
var conditionalTree = new ConditionalTree
{
Root = new ConditionalTree.ConditionalNode()
};
var attributes = new List<int>();
for (int index = 0; index < _data.Attributes.Length; index++)
{
if (_data.Attributes[index] == TableData.ClassAttributeName)
{
continue;
}
attributes.Add(index);
}
//BuildConditionalNodesRecursive(listRows, attributes, conditionalTree.Root);
BuildConditionalNodes(listRows, attributes, conditionalTree.Root);
return conditionalTree;
}
public ConditionalTree BuildConditionalTree(ITableData data)
{
var listRows = data.ToList();
if (listRows.Count == 0)
{
return null;
}
var firstRow = listRows[0];
var conditionaTree = new ConditionalTree
{
Root = new ConditionalTree.ConditionalNode()
};
var attributes = firstRow.Attributes.ToList();
attributes.Remove(TableData.ClassAttributeName);
BuildConditionalNodesRecursive(listRows, attributes, conditionaTree.Root);
return conditionaTree;
}
private void BuildConditionalNodesRecursive(IList<IDataRow> rows, IList<string> attributes,
ConditionalTree.ConditionalNode parentNode)
{
var attributesList = attributes.ToList();
if (attributesList.Count == 0)
{
return;
}
bool sameClass;
var result = ComputeBestGain(rows, attributes, out sameClass);
if (sameClass)
{
parentNode.Class = rows.First().Class;
return;
}
var attributeResult = result.Item2;
var first = true;
var children = new List<ConditionalTree.ConditionalNode>();
attributesList.Remove(attributeResult.Attribute);
foreach (var subset in attributeResult.Subsets)
{
var node = new ConditionalTree.ConditionalNode
{
Condition = attributeResult.IsNumeric
? first
? ConditionalTree.PredicateCondition.LessThanOrEqual
: ConditionalTree.PredicateCondition.GreaterThan
: ConditionalTree.PredicateCondition.Equal,
ThreshHold = subset.Value,
Attribute = attributeResult.Attribute
};
BuildConditionalNodesRecursive(subset.Rows, attributesList, node);
first = false;
children.Add(node);
}
parentNode.Children = children;
}
private void BuildConditionalNodes(IList<int> rows, IList<int> attributesIndexes,
ConditionalTree.ConditionalNode parentNode)
{
var stack = new Stack<Iteration>();
stack.Push(new Iteration
{
Attributes = attributesIndexes,
ParentNode = parentNode,
Rows = rows,
});
Iteration currentIteration = stack.Pop();
while (currentIteration != null)
{
var attributesList = currentIteration.Attributes.ToList();
if (attributesList.Count == 0)
{
currentIteration = stack.Count > 0 ? stack.Pop() : null;
continue;
}
bool sameClass;
var result = ComputeBestGain(currentIteration.Rows, currentIteration.Attributes,
out sameClass);
if (sameClass)
{
currentIteration.ParentNode.Class = _data.ClassesValue[_data.Class(currentIteration.Rows[0])];
currentIteration = stack.Count > 0 ? stack.Pop() : null;
continue;
}
var attributeResult = result.Item2;
var first = true;
var children = new List<ConditionalTree.ConditionalNode>();
attributesList.Remove(attributeResult.AttributeIndex);
foreach (var subset in attributeResult.Subsets)
{
var node = new ConditionalTree.ConditionalNode
{
Condition = attributeResult.IsNumeric
? first
? ConditionalTree.PredicateCondition.LessThanOrEqual
: ConditionalTree.PredicateCondition.GreaterThan
: ConditionalTree.PredicateCondition.Equal,
ThreshHold = subset.Value,
Attribute = _data.Attributes[attributeResult.AttributeIndex]
};
stack.Push(new Iteration
{
Rows = subset.Rows,
Attributes = attributesList,
ParentNode = node,
});
first = false;
children.Add(node);
}
currentIteration.ParentNode.Children = children;
currentIteration = stack.Count > 0 ? stack.Pop() : null;
}
}