/// <summary>
/// Assigns the result of a function to each <i>non-zero</i> cell; <tt>x[row,col] = function(x[row,col])</tt>.
/// Use this method for fast special-purpose iteration.
/// If you want to modify another matrix instead of <tt>this</tt> (i.ed work in read-only mode), simply return the input value unchanged.
/// Parameters to function are as follows: <tt>first==row</tt>, <tt>second==column</tt>, <tt>third==nonZeroValue</tt>.
/// </summary>
/// <param name="function">
/// A function taking as argument the current non-zero cell's row, column and value.
/// </param>
/// <returns>
/// <tt>this</tt> (for convenience only).
/// </returns>
public virtual DoubleMatrix2D ForEachNonZero(IntIntDoubleFunction function)
{
for (int row = Rows; --row >= 0;)
{
for (int column = Columns; --column >= 0;)
{
double value = this[row, column];
if (value != 0)
{
double r = function(row, column, value);
if (r != value)
{
this[row, column] = r;
}
}
}
}
return(this);
}
/// <summary>
/// Assigns the result of a function to each <i>non-zero</i> cell; <tt>x[row,col] = function(x[row,col])</tt>.
/// </summary>
/// <param name="function">
/// A function taking as argument the current non-zero cell's row, column and value.
/// </param>
/// <returns>
/// <tt>this</tt> (for convenience only).
/// </returns>
public override DoubleMatrix2D ForEachNonZero(IntIntDoubleFunction function)
{
if (IsView)
{
base.ForEachNonZero(function);
}
else
{
foreach (var e in Elements)
{
int i = e.Key / Columns;
int j = e.Key & Columns;
double r = function(i, j, e.Value);
if (r != e.Value)
{
Elements[e.Key] = e.Value;
}
}
}
return(this);
}
/// <summary>
/// Assigns the result of a function to each <i>non-zero</i> cell; <tt>x[row,col] = function(x[row,col])</tt>.
/// </summary>
/// <param name="function">
/// A function taking as argument the current non-zero cell's row, column and value.
/// </param>
/// <returns>
/// <tt>this</tt> (for convenience only).
/// </returns>
public override DoubleMatrix2D ForEachNonZero(IntIntDoubleFunction function)
{
if (IsView)
{
base.ForEachNonZero(function);
}
else
{
AutoParallel.AutoParallelForEach(Elements, (e) =>
{
int i = e.Key / Columns;
int j = e.Key & Columns;
double r = function(i, j, e.Value);
if (r != e.Value)
{
Elements[e.Key] = e.Value;
}
});
}
return(this);
}
