private static TreeNode GetRootNode(DataTable data, string edge)
{
var attributes = new List <MyAttribute>();
var highestInformationGainIndex = -1;
var highestInformationGain = double.MinValue;
// Get all names, amount of attributes and attributes for every column
for (var i = 0; i < data.Columns.Count - 1; i++)
{
var differentAttributenames = MyAttribute.GetDifferentAttributeNamesOfColumn(data, i);
attributes.Add(new MyAttribute(data.Columns[i].ToString(), differentAttributenames));
}
// Calculate Entropy (S)
var tableEntropy = CalculateTableEntropy(data);
for (var i = 0; i < attributes.Count; i++)
{
attributes[i].InformationGain = GetGainForAllAttributes(data, i, tableEntropy);
if (attributes[i].InformationGain > highestInformationGain)
{
highestInformationGain = attributes[i].InformationGain;
highestInformationGainIndex = i;
}
}
return(new TreeNode(attributes[highestInformationGainIndex].Name, highestInformationGainIndex, attributes[highestInformationGainIndex], edge));
}
public static DataTable ImportFromCsvFile(string filePath)
{
var rows = 0;
var data = new DataTable();
try
{
using (var reader = new StreamReader(File.OpenRead(filePath)))
{
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
var values = line.Substring(0, line.Length - 1).Split(';');
foreach (var item in values)
{
if (string.IsNullOrEmpty(item) || string.IsNullOrWhiteSpace(item))
{
throw new Exception("Value can't be empty");
}
if (rows == 0)
{
data.Columns.Add(item);
}
}
if (rows > 0)
{
data.Rows.Add(values);
}
rows++;
if (values.Length != data.Columns.Count)
{
throw new Exception("Row is shorter or longer than title row");
}
}
}
var differentValuesOfLastColumn =
MyAttribute.GetDifferentAttributeNamesOfColumn(data, data.Columns.Count - 1);
Console.WriteLine("data.Columns.Count -> " + data.Columns.Count);
Console.WriteLine("differentValuesOfLastColumn.Count -> " + differentValuesOfLastColumn.Count);
if (differentValuesOfLastColumn.Count > 4)
{
throw new Exception("The last column is the result column and can contain only 4 different values");
}
}
catch (Exception ex)
{
DisplayErrorMessage(ex.Message);
data = null;
}
// if no rows are entered or data == null, return null
return(data?.Rows.Count > 0 ? data : null);
}
public TreeNode(string name, int tableIndex, MyAttribute nodeAttribute, string edge)
{
Name = name;
TableIndex = tableIndex;
NodeAttribute = nodeAttribute;
ChildNodes = new List <TreeNode>();
Edge = edge;
}
