Skip to content

CompareRandomGeneratorsCxx

vtk-examples/Cxx/Plotting/CompareRandomGeneratorsCxx


Description

This example demonstrates 6 random number generators offered by c++11. These are now part of the C++ standard. They offer a different API and more generators than presented the vtk generators vtkMinimalStandardRandomSequence, vtkBoxMuellerRandomSequence, vtkGaussianRandomSequence and vtkMersenneTwister.

The vtkRandomSequence generators are used internally by vtk classes, but application developers may prefer to use the C++ standard generators.

The c++ standard random number collections is described here.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

CompareRandomGeneratorsCxx.cxx

#include <vtkActor.h>
#include <vtkActor2D.h>
#include <vtkBarChartActor.h>
#include <vtkDataObject.h>
#include <vtkFieldData.h>
#include <vtkIntArray.h>
#include <vtkLegendBoxActor.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkProperty2D.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkTextMapper.h>
#include <vtkTextProperty.h>

#include <algorithm>
#include <map>
#include <random>
#include <vector>

namespace {
vtkSmartPointer<vtkIntArray> CreateUniformDistribution(int, double, double);
vtkSmartPointer<vtkIntArray> CreateNormalDistribution(int, double, double);
vtkSmartPointer<vtkIntArray> CreateWeibullDistribution(int, double, double);
vtkSmartPointer<vtkIntArray> CreateGammaDistribution(int, double, double);
vtkSmartPointer<vtkIntArray> CreateCauchyDistribution(int, double, double);
vtkSmartPointer<vtkIntArray> CreateExtremeValueDistribution(int, double,
                                                            double);
} // namespace
int main(int, char*[])
{

  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkRenderWindow> renderWindow;

  int count = 100000;
  std::map<std::string, vtkSmartPointer<vtkIntArray>> frequencies;
  frequencies["Uniform Distribution"] =
      CreateUniformDistribution(count, -200.0, 200.0);
  frequencies["Normal Distribution"] =
      CreateNormalDistribution(count, 0.0, 6.0);
  frequencies["Weibull Distribution"] =
      CreateWeibullDistribution(count, 1.5, 1.0);
  frequencies["Gamma Distribution"] = CreateGammaDistribution(count, 2.0, 2.0);
  frequencies["Cauchy Distribution"] =
      CreateCauchyDistribution(count, -1.0, 2.0);
  frequencies["Extreme Value Distribution"] =
      CreateExtremeValueDistribution(count, .5, 1.0);

  std::vector<vtkSmartPointer<vtkRenderer>> renderers;

  for (auto fit = frequencies.begin(); fit != frequencies.end(); fit++)
  {
    vtkNew<vtkBarChartActor> chart;

    vtkNew<vtkDataObject> dataObject;
    dataObject->GetFieldData()->AddArray(fit->second);

    chart->SetInput(dataObject);
    chart->SetTitle(fit->first.c_str());
    chart->GetPositionCoordinate()->SetValue(0.05, 0.05, 0.0);
    chart->GetPosition2Coordinate()->SetValue(0.95, 0.85, 0.0);
    chart->GetProperty()->SetColor(colors->GetColor3d("Yellow").GetData());
    chart->LegendVisibilityOff();
    chart->LabelVisibilityOff();
    chart->TitleVisibilityOff();
    for (int c = 0; c < count; ++c)
    {
      chart->SetBarColor(c, colors->GetColor3d("MidnightBlue").GetData());
    }
    // Create a title
    vtkNew<vtkTextProperty> titleProperty;
    titleProperty->SetFontSize(16);
    titleProperty->SetJustificationToCentered();

    vtkNew<vtkTextMapper> titleMapper;
    titleMapper->SetInput(fit->first.c_str());
    titleMapper->SetTextProperty(titleProperty);

    vtkNew<vtkActor2D> titleActor;
    titleActor->SetMapper(titleMapper);
    titleActor->GetPositionCoordinate()
        ->SetCoordinateSystemToNormalizedViewport();
    titleActor->GetPositionCoordinate()->SetValue(.5, .85, 0.0);
    titleActor->GetProperty()->SetColor(
        colors->GetColor3d("MidnightBlue").GetData());

    vtkNew<vtkRenderer> renderer;
    renderer->AddActor(chart);
    renderer->AddActor(titleActor);
    renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
    renderers.push_back(renderer);
    renderWindow->AddRenderer(renderer);
  }

  // Setup a grid of renderers
  int gridCols = 3;
  int gridRows = 2;

  // Define side length (in pixels) of each renderer square
  int rendererSize = 300;

  renderWindow->SetWindowName("CompareRandomGeneratorsCxx");
  renderWindow->SetSize(rendererSize * gridCols, rendererSize * gridRows);

  // Set up a grid of viewports for each renderer
  int r = 0;
  for (double row = 0; row < gridRows; row++)
  {
    for (double col = 0; col < gridCols; col++)
    {
      double index = row * gridCols + col;

      // Set the renderer's viewport dimensions (xmin, ymin, xmax, ymax) within
      // the render window. Note that for the Y values, we need to subtract the
      // row index from gridRows because the viewport Y axis points upwards, but
      // we want to draw the grid from top to down
      double viewport[4] = {static_cast<double>(col) / gridCols,
                            static_cast<double>(gridRows - row - 1) / gridRows,
                            static_cast<double>(col + 1) / gridCols,
                            static_cast<double>(gridRows - row) / gridRows};
      renderers[r]->SetViewport(viewport);
      ++r;
    }
  }

  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(renderWindow);

  renderWindow->Render();

  // Initialize the event loop and then start it
  interactor->Initialize();
  interactor->Start();

  return EXIT_SUCCESS;
}
namespace {
vtkSmartPointer<vtkIntArray> CreateUniformDistribution(int count, double a,
                                                       double b)
{
  std::mt19937 generator(8775070);
  double rmin, rmax;
  rmax = b;
  rmin = a;
  std::uniform_real_distribution<double> distribution(a, b);

  double range = (rmax - rmin);
  int numberOfBins = std::max(51, (int)std::ceil(range / 10));

  std::vector<int> frequencies(numberOfBins, 0);
  for (int i = 0; i < count; ++i)
  {
    double value = (distribution(generator) - rmin) / range;
    int bin = (int)(std::floor((numberOfBins)*value));
    if (bin > numberOfBins - 1)
    {
      bin = numberOfBins - 1;
    }
    else if (bin < 0)
    {
      bin = 0;
    }
    ++frequencies[bin];
  }
  frequencies[numberOfBins - 1] = 0;

  vtkNew<vtkIntArray> frequenciesArray;
  frequenciesArray->SetNumberOfComponents(1);
  frequenciesArray->SetNumberOfTuples(numberOfBins);

  for (int i = 0; i < numberOfBins; ++i)
  {
    frequenciesArray->SetTypedTuple(i, &frequencies[i]);
  }
  frequenciesArray->SetName("frequencies");

  return frequenciesArray;
}

vtkSmartPointer<vtkIntArray> CreateNormalDistribution(int count, double a,
                                                      double b)
{
  double rmin, rmax;
  std::mt19937 generator(8775070);
  std::normal_distribution<double> distribution(a, b);
  rmax = 6.0 * b;
  rmin = -6.0 * b;

  double range = (rmax - rmin);
  int numberOfBins = std::max(51, (int)std::ceil(range / 10));

  std::vector<int> frequencies(numberOfBins, 0);
  for (int i = 0; i < count; ++i)
  {
    double value = (distribution(generator) - rmin) / range;
    int bin = (int)(std::floor((numberOfBins)*value));
    if (bin > numberOfBins - 1)
    {
      bin = numberOfBins - 1;
    }
    else if (bin < 0)
    {
      bin = 0;
    }
    ++frequencies[bin];
  }
  frequencies[numberOfBins - 1] = 0;

  vtkNew<vtkIntArray> frequenciesArray;
  frequenciesArray->SetNumberOfComponents(1);
  frequenciesArray->SetNumberOfTuples(numberOfBins);

  for (int i = 0; i < numberOfBins; ++i)
  {
    frequenciesArray->SetTypedTuple(i, &frequencies[i]);
  }
  frequenciesArray->SetName("frequencies");

  return frequenciesArray;
}
vtkSmartPointer<vtkIntArray> CreateWeibullDistribution(int count, double a,
                                                       double b)
{
  double rmin, rmax;
  std::mt19937 generator(8775070);
  std::weibull_distribution<double> distribution(a, b);
  rmax = 3.0;
  rmin = 0.0;

  double range = (rmax - rmin);
  int numberOfBins = std::max(51, (int)std::ceil(range / 10));

  std::vector<int> frequencies(numberOfBins, 0);
  for (int i = 0; i < count; ++i)
  {
    double value = (distribution(generator) - rmin) / range;
    int bin = (int)(std::floor((numberOfBins)*value));
    if (bin > numberOfBins - 1)
    {
      bin = numberOfBins - 1;
    }
    else if (bin < 0)
    {
      bin = 0;
    }
    ++frequencies[bin];
  }
  frequencies[numberOfBins - 1] = 0;

  vtkNew<vtkIntArray> frequenciesArray;
  frequenciesArray->SetNumberOfComponents(1);
  frequenciesArray->SetNumberOfTuples(numberOfBins);

  for (int i = 0; i < numberOfBins; ++i)
  {
    frequenciesArray->SetTypedTuple(i, &frequencies[i]);
  }
  frequenciesArray->SetName("frequencies");

  return frequenciesArray;
}
vtkSmartPointer<vtkIntArray> CreateGammaDistribution(int count, double a,
                                                     double b)
{
  double rmin, rmax;
  std::mt19937 generator(8775070);
  std::gamma_distribution<double> distribution(a, b);
  rmax = 20.0;
  rmin = 0.0;

  double range = (rmax - rmin);
  int numberOfBins = std::max(51, (int)std::ceil(range / 10));

  std::vector<int> frequencies(numberOfBins, 0);
  for (int i = 0; i < count; ++i)
  {
    double value = (distribution(generator) - rmin) / range;
    int bin = (int)(std::floor((numberOfBins)*value));
    if (bin > numberOfBins - 1)
    {
      bin = numberOfBins - 1;
    }
    else if (bin < 0)
    {
      bin = 0;
    }
    ++frequencies[bin];
  }
  frequencies[numberOfBins - 1] = 0;

  vtkNew<vtkIntArray> frequenciesArray;
  frequenciesArray->SetNumberOfComponents(1);
  frequenciesArray->SetNumberOfTuples(numberOfBins);

  for (int i = 0; i < numberOfBins; ++i)
  {
    frequenciesArray->SetTypedTuple(i, &frequencies[i]);
  }
  frequenciesArray->SetName("frequencies");

  return frequenciesArray;
}

vtkSmartPointer<vtkIntArray> CreateCauchyDistribution(int count, double a,
                                                      double b)
{
  double rmin, rmax;
  std::mt19937 generator(8775070);
  std::cauchy_distribution<double> distribution(a, b);

  rmin = -10;
  rmax = 15.0;

  double range = (rmax - rmin);
  int numberOfBins = std::max(51, (int)std::ceil(range / 10));

  std::vector<int> frequencies(numberOfBins, 0);
  for (int i = 0; i < count; ++i)
  {
    double value = (distribution(generator) - rmin) / range;
    int bin = (int)(std::floor((numberOfBins)*value));
    if (bin > numberOfBins - 1)
    {
      bin = numberOfBins - 1;
    }
    else if (bin < 0)
    {
      bin = 0;
    }
    ++frequencies[bin];
  }
  frequencies[0] = frequencies[1];
  frequencies[numberOfBins - 1] = frequencies[numberOfBins - 2];

  vtkNew<vtkIntArray> frequenciesArray;
  frequenciesArray->SetNumberOfComponents(1);
  frequenciesArray->SetNumberOfTuples(numberOfBins);

  for (int i = 0; i < numberOfBins; ++i)
  {
    frequenciesArray->SetTypedTuple(i, &frequencies[i]);
  }
  frequenciesArray->SetName("frequencies");

  return frequenciesArray;
}
vtkSmartPointer<vtkIntArray> CreateExtremeValueDistribution(int count, double a,
                                                            double b)
{
  double rmin, rmax;
  std::mt19937 generator(8775070);

  std::extreme_value_distribution<double> distribution(a, b);
  rmax = 5.0;
  rmin = -2.0;

  double range = (rmax - rmin);
  int numberOfBins = std::max(51, (int)std::ceil(range / 10));

  std::vector<int> frequencies(numberOfBins, 0);
  for (int i = 0; i < count; ++i)
  {
    double value = (distribution(generator) - rmin) / range;
    int bin = (int)(std::floor((numberOfBins)*value));
    if (bin > numberOfBins - 1)
    {
      bin = numberOfBins - 1;
    }
    else if (bin < 0)
    {
      bin = 0;
    }
    ++frequencies[bin];
  }
  frequencies[numberOfBins - 1] = 0;

  vtkNew<vtkIntArray> frequenciesArray;
  frequenciesArray->SetNumberOfComponents(1);
  frequenciesArray->SetNumberOfTuples(numberOfBins);

  for (int i = 0; i < numberOfBins; ++i)
  {
    frequenciesArray->SetTypedTuple(i, &frequencies[i]);
  }
  frequenciesArray->SetName("frequencies");

  return frequenciesArray;
}
} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(CompareRandomGeneratorsCxx)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  InteractionStyle
  RenderingAnnotation
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "CompareRandomGeneratorsCxx: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(CompareRandomGeneratorsCxx MACOSX_BUNDLE CompareRandomGeneratorsCxx.cxx )
  target_link_libraries(CompareRandomGeneratorsCxx PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS CompareRandomGeneratorsCxx
  MODULES ${VTK_LIBRARIES}
)

Download and Build CompareRandomGeneratorsCxx

Click here to download CompareRandomGeneratorsCxx and its CMakeLists.txt file. Once the tarball CompareRandomGeneratorsCxx.tar has been downloaded and extracted,

cd CompareRandomGeneratorsCxx/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./CompareRandomGeneratorsCxx

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.