//---------------------------------------------------------------------------------------
//This function computes the DISTANCE matrix and inserts it into the database
//This is the distance between the two columns of the Rating Matrix
//---------------------------------------------------------------------------------------
public void ComputeDIST(Predict_DAO_MCol dao)
{
//dao.CLEAN_DIST_Matrix();
List<string> list_ClusterID = dao.getAllClusterID();
foreach (var item in list_ClusterID)
{
Dictionary<string, int> RM_dic_users = new Dictionary<string, int>();
Dictionary<string, int> RM_dic_items = new Dictionary<string, int>();
// Compute ratting matrix
List<MatrixItem> lstRMI = dao.getRattingMatrixItem_ByClusterID(item);
double[][] RattingMatrix = Util.toMatrix_MatrixItem(lstRMI, out RM_dic_users, out RM_dic_items);
if (RattingMatrix.Length > 0 & RM_dic_items.Count > 1)
{
double[][] DIST = new double[RattingMatrix[0].Length][];
for (int i = 0; i < RattingMatrix[0].Length; i++)
DIST[i] = new double[RattingMatrix[0].Length];
// Compute DIST Matrix
for (int i1 = 0; i1 < RattingMatrix[0].Length - 1; i1++)
for (int i2 = i1 + 1; i2 < RattingMatrix[0].Length; i2++)
{
double value = 0.0;
for (int t = 0; t < RattingMatrix.Length; t++)
value += Math.Pow(RattingMatrix[t][i1] - RattingMatrix[t][i2], 2);
value = Math.Sqrt(value);
DIST[i1][i2] = value;
DIST[i2][i1] = value;
}
if (DIST.Length > 0)
{
double max = DIST[0][0];
// Find Max
for (int i = 0; i < DIST.Length; i++)
{
double localMax = DIST[i].Max();
if (localMax > max)
max = localMax;
}
// Standardization
if (max != 0)
{
for (int i = 0; i < DIST.Length; i++)
for (int j = 0; j < DIST[0].Length; j++)
DIST[i][j] /= max;
}
// Save to Database
for (int i = 0; i < DIST.Length; i++)
for (int j = 0; j < DIST[0].Length; j++)
if (DIST[i][j] > 0)
{
MatrixItem matrixItem = new MatrixItem();
matrixItem.Row = Util.FindKeyByValue(RM_dic_items, i);
matrixItem.Column = Util.FindKeyByValue(RM_dic_items, j);
matrixItem.Cell = DIST[i][j];
matrixItem.ClusterID = item;
dao.setDIST_Matrix(matrixItem);
}
}
}
}
}