Added support for general p-norms to vtkNormalizeMatrixVectors

Previously, vtkNormalizeMatrixVectors only supported 2-norms,
which are still the default.

Infovis/vtkNormalizeMatrixVectors.cxx

@@ -34,7 +34,8 @@
 vtkStandardNewMacro(vtkNormalizeMatrixVectors);
 
 vtkNormalizeMatrixVectors::vtkNormalizeMatrixVectors() :
-  VectorDimension(1)
+  VectorDimension(1),
+  PValue(2)
 {
 }
 
@@ -46,6 +47,7 @@ void vtkNormalizeMatrixVectors::PrintSelf(ostream& os, vtkIndent indent)
 {
   this->Superclass::PrintSelf(os, indent);
   os << indent << "VectorDimension: " << this->VectorDimension << endl;
+  os << indent << "PValue: " << this->PValue << endl;
 }
 
 int vtkNormalizeMatrixVectors::RequestData(
@@ -54,6 +56,7 @@ int vtkNormalizeMatrixVectors::RequestData(
   vtkInformationVector* outputVector)
 {
   int vector_dimension = vtkstd::min(1, vtkstd::max(0, this->VectorDimension));
+  double p_value = vtkstd::max(1.0, this->PValue);
 
   vtkArrayData* const input = vtkArrayData::GetData(inputVector[0]);
   if(input->GetNumberOfArrays() != 1)
@@ -88,13 +91,13 @@ int vtkNormalizeMatrixVectors::RequestData(
   for(vtkIdType n = 0; n != value_count; ++n)
     {
     output_array->GetCoordinatesN(n, coordinates);
-    weight[coordinates[vector_dimension] - vectors.GetBegin()] += pow(output_array->GetValueN(n), 2);
+    weight[coordinates[vector_dimension] - vectors.GetBegin()] += pow(output_array->GetValueN(n), p_value);
     }
 
   // Convert the sums into weights, avoiding divide-by-zero ...
   for(vtkIdType i = 0; i != vectors.GetSize(); ++i)
     {
-    const double length = sqrt(weight[i]);
+    const double length = pow(weight[i],1.0/p_value);
     weight[i] = length ? 1.0 / length : 0.0;
     }
 

Infovis/vtkNormalizeMatrixVectors.h

@@ -20,7 +20,8 @@
 =========================================================================*/
 
 // .NAME vtkNormalizeMatrixVectors - given a sparse input matrix, produces
-// a sparse output matrix with each vector normalized to unit length.
+// a sparse output matrix with each vector normalized to unit length with respect 
+// to a p-norm (default p=2).
 //
 // .SECTION Thanks
 // Developed by Timothy M. Shead (tshead@sandia.gov) at Sandia National Laboratories.
@@ -42,6 +43,11 @@ public:
   vtkGetMacro(VectorDimension, int);
   vtkSetMacro(VectorDimension, int);
 
+  // Description:
+  // Value of p in p-norm normalization, subject to p >= 1.  Default is p=2 (Euclidean norm).
+  vtkGetMacro(PValue, double);
+  vtkSetMacro(PValue, double);
+
 protected:
   vtkNormalizeMatrixVectors();
   ~vtkNormalizeMatrixVectors();
@@ -52,6 +58,7 @@ protected:
     vtkInformationVector*);
 
   int VectorDimension;
+  double PValue;
 
 private:
   vtkNormalizeMatrixVectors(const vtkNormalizeMatrixVectors&); // Not implemented