/// <summary>
/// Create or get an element in the row
/// </summary>
/// <param name="row">Row (used for creating a new element)</param>
/// <param name="column">Column</param>
/// <param name="result">The found or created element</param>
/// <returns>True if the element was found, false if it was created</returns>
public bool CreateGetElement(int row, int column, out SparseMatrixElement <T> result)
{
result = null;
SparseMatrixElement <T> element = FirstInRow, lastElement = null;
while (element != null)
{
if (element.Column > column)
{
break;
}
if (element.Column == column)
{
// Found the element
result = element;
return(true);
}
lastElement = element;
element = element.NextInRow;
}
// Create a new element
result = new SparseMatrixElement <T>(row, column);
// Update links for last element
if (lastElement == null)
{
FirstInRow = result;
}
else
{
lastElement.NextInRow = result;
}
result.PreviousInRow = lastElement;
// Update links for next element
if (element == null)
{
LastInRow = result;
}
else
{
element.PreviousInRow = result;
}
result.NextInRow = element;
// Could not find existing element
return(false);
}
/// <summary>
/// Create or get an element in the column
/// </summary>
/// <param name="row">Row</param>
/// <param name="column">Column (used for creating a new element)</param>
/// <param name="result">The found or created element</param>
/// <returns>True if the element was found, false if it was created</returns>
public bool CreateGetElement(int row, int column, out SparseMatrixElement <T> result)
{
SparseMatrixElement <T> element = FirstInColumn, lastElement = null;
while (element != null)
{
if (element.Row > row)
{
break;
}
if (element.Row == row)
{
result = element;
return(true);
}
lastElement = element;
element = element.NextInColumn;
}
// Create a new element
result = new SparseMatrixElement <T>(row, column);
// Update links for last element
if (lastElement == null)
{
FirstInColumn = result;
}
else
{
lastElement.NextInColumn = result;
}
result.PreviousInColumn = lastElement;
// Update links for next element
if (element == null)
{
LastInColumn = result;
}
else
{
element.PreviousInColumn = result;
}
result.NextInColumn = element;
// Did not find element
return(false);
}
/// <summary>
/// Find an element in the row without creating it, returns null if it doesn't exist
/// </summary>
/// <param name="column">Column</param>
public SparseMatrixElement <T> Find(int column)
{
SparseMatrixElement <T> element = FirstInRow;
while (element != null)
{
if (element.Column == column)
{
return(element);
}
if (element.Column > column)
{
return(null);
}
element = element.NextInRow;
}
return(null);
}
/// <summary>
/// Find an element in the column without creating it, returns null if it doesn't exist
/// </summary>
/// <param name="row">Row</param>
public SparseMatrixElement <T> Find(int row)
{
SparseMatrixElement <T> element = FirstInColumn;
while (element != null)
{
if (element.Row == row)
{
return(element);
}
if (element.Row > row)
{
return(null);
}
element = element.NextInColumn;
}
return(null);
}
/// <summary>
/// Remove an element from the row
/// </summary>
/// <param name="element">Element</param>
public void Remove(SparseMatrixElement <T> element)
{
if (element.PreviousInRow == null)
{
FirstInRow = element.NextInRow;
}
else
{
element.PreviousInRow.NextInRow = element.NextInRow;
}
if (element.NextInRow == null)
{
LastInRow = element.PreviousInRow;
}
else
{
element.NextInRow.PreviousInRow = element.PreviousInRow;
}
}
/// <summary>
/// Remove an element from the row
/// </summary>
/// <param name="element">Element</param>
public void Remove(SparseMatrixElement <T> element)
{
if (element.PreviousInColumn == null)
{
FirstInColumn = element.NextInColumn;
}
else
{
element.PreviousInColumn.NextInColumn = element.NextInColumn;
}
if (element.NextInColumn == null)
{
LastInColumn = element.PreviousInColumn;
}
else
{
element.NextInColumn.PreviousInColumn = element.PreviousInColumn;
}
}
/// <summary>
/// Insert an element in the row
/// This method assumes an element does not exist at its indices!
/// </summary>
/// <param name="newElement">New element</param>
public void Insert(SparseMatrixElement <T> newElement)
{
int column = newElement.Column;
SparseMatrixElement <T> element = FirstInRow, lastElement = null;
while (element != null)
{
if (element.Column > column)
{
break;
}
lastElement = element;
element = element.NextInRow;
}
// Update links for last element
if (lastElement == null)
{
FirstInRow = newElement;
}
else
{
lastElement.NextInRow = newElement;
}
newElement.PreviousInRow = lastElement;
// Update links for next element
if (element == null)
{
LastInRow = newElement;
}
else
{
element.PreviousInRow = newElement;
}
newElement.NextInRow = element;
}
/// <summary>
/// Swap two elements in the row, <paramref name="first"/> and <paramref name="columnFirst"/> are supposed to come first in the row.
/// Does not update column pointers!
/// </summary>
/// <param name="first">First matrix element</param>
/// <param name="second">Second matrix element</param>
/// <param name="columnFirst">First column</param>
/// <param name="columnSecond">Second column</param>
public void Swap(SparseMatrixElement <T> first, SparseMatrixElement <T> second, int columnFirst, int columnSecond)
{
if (first == null && second == null)
{
throw new ArgumentException("Both matrix elements cannot be null");
}
if (first == null)
{
// Do we need to move the element?
if (second.PreviousInRow == null || second.PreviousInRow.Column < columnFirst)
{
second.Column = columnFirst;
return;
}
// Move the element back
SparseMatrixElement <T> element = second.PreviousInRow;
Remove(second);
while (element.PreviousInRow != null && element.PreviousInRow.Column > columnFirst)
{
element = element.PreviousInRow;
}
// We now have the first element below the insertion point
if (element.PreviousInRow == null)
{
FirstInRow = second;
}
else
{
element.PreviousInRow.NextInRow = second;
}
second.PreviousInRow = element.PreviousInRow;
element.PreviousInRow = second;
second.NextInRow = element;
second.Column = columnFirst;
}
else if (second == null)
{
// Do we need to move the element?
if (first.NextInRow == null || first.NextInRow.Column > columnSecond)
{
first.Column = columnSecond;
return;
}
// Move the element forward
SparseMatrixElement <T> element = first.NextInRow;
Remove(first);
while (element.NextInRow != null && element.NextInRow.Column < columnSecond)
{
element = element.NextInRow;
}
// We now have the first element above the insertion point
if (element.NextInRow == null)
{
LastInRow = first;
}
else
{
element.NextInRow.PreviousInRow = first;
}
first.NextInRow = element.NextInRow;
element.NextInRow = first;
first.PreviousInRow = element;
first.Column = columnSecond;
}
else
{
// Are they adjacent or not?
if (first.NextInRow == second)
{
// Correct surrounding links
if (first.PreviousInRow == null)
{
FirstInRow = second;
}
else
{
first.PreviousInRow.NextInRow = second;
}
if (second.NextInRow == null)
{
LastInRow = first;
}
else
{
second.NextInRow.PreviousInRow = first;
}
// Correct element links
first.NextInRow = second.NextInRow;
second.PreviousInRow = first.PreviousInRow;
first.PreviousInRow = second;
second.NextInRow = first;
first.Column = columnSecond;
second.Column = columnFirst;
}
else
{
// Swap surrounding links
if (first.PreviousInRow == null)
{
FirstInRow = second;
}
else
{
first.PreviousInRow.NextInRow = second;
}
first.NextInRow.PreviousInRow = second;
if (second.NextInRow == null)
{
LastInRow = first;
}
else
{
second.NextInRow.PreviousInRow = first;
}
second.PreviousInRow.NextInRow = first;
// Swap element links
SparseMatrixElement <T> element = first.PreviousInRow;
first.PreviousInRow = second.PreviousInRow;
second.PreviousInRow = element;
element = first.NextInRow;
first.NextInRow = second.NextInRow;
second.NextInRow = element;
first.Column = columnSecond;
second.Column = columnFirst;
}
}
}
