/// <summary>
/// Create a view of the parent matrix in which rows become cols and cols become rows.
/// This is a 'view' in the sense that changes to the values in either matrix will be reflected in both.
/// </summary>
/// <remarks>If two layers of TransposeView are applied to a parent matrix, the parent matrix is returned.</remarks>
/// <typeparam name="TRowKey">The type of the row key. Usually "String"</typeparam>
/// <typeparam name="TColKey">The type of the col key. Usually "String"</typeparam>
/// <typeparam name="TValue">The type of the value, for example, double, int, char, etc.</typeparam>
/// <param name="parentMatrix">The matrix to wrap.</param>
/// <returns>A transposed matrix</returns>
static public Matrix <TColKey, TRowKey, TValue> TransposeView <TRowKey, TColKey, TValue>(
this Matrix <TRowKey, TColKey, TValue> parentMatrix)
{
//If this is a transpose of a transpose, simplify
TransposeView <TRowKey, TColKey, TValue> parentTransposeViewOrNull = parentMatrix as TransposeView <TRowKey, TColKey, TValue>;
if (null != parentTransposeViewOrNull)
{
return(parentTransposeViewOrNull.ParentMatrix);
}
var transposeView = new TransposeView <TColKey, TRowKey, TValue>();
transposeView.ParentMatrix = parentMatrix;
return(transposeView);
}
private static DenseMatrix <TRowKey, TColKey, TValue> MaterializeTransposeViewToDenseMatrix <TRowKey, TColKey, TValue>(TransposeView <TRowKey, TColKey, TValue> transposeView)
{
DenseMatrix <TColKey, TRowKey, TValue> parent = (DenseMatrix <TColKey, TRowKey, TValue>)transposeView.ParentMatrix;
var matrix = new DenseMatrix <TRowKey, TColKey, TValue>();
matrix._rowKeys = transposeView.RowKeys;
matrix._colKeys = transposeView.ColKeys;
matrix._indexOfRowKey = transposeView.IndexOfRowKey;
matrix._indexOfColKey = transposeView.IndexOfColKey;
matrix._missingValue = parent.MissingValue;
matrix.ValueArray = new TValue[matrix.RowCount, matrix.ColCount];
for (int newRowIndex = 0; newRowIndex < matrix.RowCount; ++newRowIndex)
{
for (int newColIndex = 0; newColIndex < matrix.ColCount; ++newColIndex)
{
matrix.ValueArray[newRowIndex, newColIndex] = parent.ValueArray[newColIndex, newRowIndex];
}
}
return(matrix);
}
