/// <summary>
/// Returns a clone of this matrix.
/// </summary>
/// <param name="values">If true (default), the values are copied.</param>
public CompressedColumnStorage <T> Clone(bool values = true)
{
int m = this.RowCount;
int n = this.ColumnCount;
int nnz = this.NonZerosCount;
var ap = this.ColumnPointers;
var ai = this.RowIndices;
var result = CompressedColumnStorage <T> .Create(m, n, values?nnz : 0);
if (values)
{
Buffer.BlockCopy(ap, 0, result.ColumnPointers, 0, (m + 1) * Constants.SizeOfInt);
Buffer.BlockCopy(ai, 0, result.RowIndices, 0, nnz * Constants.SizeOfInt);
Array.Copy(this.Values, 0, result.Values, 0, nnz);
}
else
{
result.RowIndices = new int[nnz];
Buffer.BlockCopy(ap, 0, result.ColumnPointers, 0, (m + 1) * Constants.SizeOfInt);
Buffer.BlockCopy(ai, 0, result.RowIndices, 0, nnz * Constants.SizeOfInt);
}
return(result);
}
/// <summary>
/// Returns the transpose of this matrix.
/// </summary>
public virtual CompressedColumnStorage <T> Transpose()
{
var result = CompressedColumnStorage <T> .Create(ncols, nrows, this.NonZerosCount);
this.Transpose(result);
return(result);
}
/// <summary>
/// Convert a coordinate storage to compressed sparse column (CSC) format.
/// </summary>
/// <param name="storage">Coordinate storage.</param>
/// <param name="cleanup">Remove and sum duplicate entries.</param>
/// <returns>Compressed sparse column storage.</returns>
public static CompressedColumnStorage <T> ToCompressedColumnStorage <T>(CoordinateStorage <T> storage,
bool cleanup = true) where T : struct, IEquatable <T>, IFormattable
{
int nrows = storage.RowCount;
int ncols = storage.ColumnCount;
var values = storage.Values;
var rowind = storage.RowIndices;
var colind = storage.ColumnIndices;
int p, k, nz = storage.NonZerosCount;
var columnPointers = new int[ncols + 1];
var columnCounts = new int[ncols];
for (k = 0; k < nz; k++)
{
// Count columns
columnCounts[colind[k]]++;
}
// Get row pointers
int valueCount = Helper.CumulativeSum(columnPointers, columnCounts, ncols);
var result = CompressedColumnStorage <T> .Create(nrows, ncols);
var rowIndices = new int[valueCount];
var storageValues = new T[valueCount];
for (k = 0; k < nz; k++)
{
p = columnCounts[colind[k]]++;
rowIndices[p] = rowind[k];
storageValues[p] = values[k];
}
result.RowIndices = rowIndices;
result.ColumnPointers = columnPointers;
result.Values = storageValues;
result.SortIndices();
if (cleanup)
{
result.Cleanup();
}
return(result);
}