BoxChart

Description¶

This example demonstrates how to generate a box plot.

The example uses data from the Michelson Morley experiment. Compare the wiki example output with the Wikipedia results

Warning

The ChartBox expects an input table with exactly 5 rows per column. The 5 rows are minimum, 1st quartile, median, 3rd quartile and maximum. vtkComputeQuartiles is used to create a valid input table from the original data.

Question

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

Code¶

BoxChart.cxx

#include <vtkSmartPointer.h>

#include <vtkChartBox.h>
#include <vtkStatisticsAlgorithm.h>
#include <vtkComputeQuartiles.h>
#include <vtkContextScene.h>
#include <vtkContextView.h>
#include <vtkIntArray.h>
#include <vtkLookupTable.h>
#include <vtkPlotBox.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkStringArray.h>
#include <vtkTable.h>
#include <vtkAxis.h>
#include <vtkTextProperty.h>

//----------------------------------------------------------------------------
int main(int , char* [])
{
  // Set up a 2D scene, add an XY chart to it
  vtkSmartPointer<vtkContextView> view =
    vtkSmartPointer<vtkContextView>::New();
  view->GetRenderWindow()->SetSize(400, 400);
  view->GetRenderWindow()->SetMultiSamples(0);

  vtkSmartPointer<vtkChartBox> chart =
    vtkSmartPointer<vtkChartBox>::New();
  view->GetScene()->AddItem(chart);

  // Creates a vtkPlotBox input table
  int numParam = 5;
  vtkSmartPointer<vtkTable> inputBoxPlotTable =
    vtkSmartPointer<vtkTable>::New();

  for (int i = 0; i < numParam; i++)
  {
    char num[10];
    sprintf(num, "Run %d", i + 1);
    vtkSmartPointer<vtkIntArray> arrIndex =
      vtkSmartPointer<vtkIntArray>::New();
    arrIndex->SetName(num);
    inputBoxPlotTable->AddColumn(arrIndex);
  }

  inputBoxPlotTable->SetNumberOfRows(20);
  double values[20][5] =
    {
      {850,     960,     880,     890,     890},
      {740,     940,     880,     810,     840},
      {900,     960,     880,     810,     780},
      {1070,    940,     860,     820,     810},
      {930,     880,     720,     800,     760},
      {850,     800,     720,     770,     810},
      {950,     850,     620,     760,     790},
      {980,     880,     860,     740,     810},
      {980,     900,     970,     750,     820},
      {880,     840,     950,     760,     850},
      {1000,    830,     880,     910,     870},
      {980,     790,     910,     920,     870},
      {930,     810,     850,     890,     810},
      {650,     880,     870,     860,     740},
      {760,     880,     840,     880,     810},
      {810,     830,     840,     720,     940},
      {1000,    800,     850,     840,     950},
      {1000,    790,     840,     850,     800},
      {960,     760,     840,     850,     810},
      {960,     800,     840,     780,     870}
    };
  for (int j = 0; j < 20; ++j)
  {
    for (int i = 0; i < 5; ++i)
    {
      inputBoxPlotTable->SetValue(j, i, values[j][i]);
    }
  }
  vtkSmartPointer<vtkComputeQuartiles> quartiles =
    vtkSmartPointer<vtkComputeQuartiles>::New();
  quartiles->SetInputData(vtkStatisticsAlgorithm::INPUT_DATA, inputBoxPlotTable);
  quartiles->Update();

  vtkTable *outTable = quartiles->GetOutput();
  vtkSmartPointer<vtkLookupTable> lookup =
    vtkSmartPointer<vtkLookupTable>::New();
  lookup->SetNumberOfColors(5);
  lookup->SetRange(0, 4);
  lookup->Build();

  chart->GetPlot(0)->SetInputData(outTable);
  chart->SetShowLegend(true);
  chart->SetColumnVisibilityAll(true);
  chart->SetTitle("Michelson-Morley experiment");
  chart->GetTitleProperties()->SetFontSize(16);
  chart->GetYAxis()->SetTitle("Speed of Light (km/s - 299000)");

  // Set the labels
  vtkSmartPointer<vtkStringArray> labels =
    vtkSmartPointer<vtkStringArray>::New();
  labels->SetNumberOfValues(5);
  labels->SetValue(0, "Run 1");
  labels->SetValue(1, "Run 2");
  labels->SetValue(2, "Run 3");
  labels->SetValue(3, "Run 4");
  labels->SetValue(4, "Run 5");
  chart->GetPlot(0)->SetLabels(labels);

  // Render the scene
  view->GetRenderWindow()->SetMultiSamples(0);
  view->GetRenderer()->SetBackground(.8, .8, .8);
  view->GetInteractor()->Initialize();
  view->Render();
  view->GetInteractor()->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(BoxChart)

find_package(VTK COMPONENTS 
  vtkChartsCore
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersStatistics
  vtkInteractionStyle
  vtkRenderingContext2D
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  vtkViewsContext2D
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping BoxChart: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(BoxChart MACOSX_BUNDLE BoxChart.cxx )
  target_link_libraries(BoxChart PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(BoxChart MACOSX_BUNDLE BoxChart.cxx )
  target_link_libraries(BoxChart PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS BoxChart
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build BoxChart¶

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

cd BoxChart/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:

./BoxChart

WINDOWS USERS

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