# ParallelCoordinatesExtraction

VTKExamples/Python/Infovis/ParallelCoordinatesExtraction

### Description

[in a Parallel Coordinates View is used to define indices to extract and view in a standard 3d render window]]([Image:ParallelCoordinatesExtraction.png|Selection)

### Code

ParallelCoordinatesExtraction.py

    #!/usr/bin/env python

    # Example of how to use Parallel Coordinates View to plot and compare
    # data set attributes,  and then to use selections in the parallel coordinates
    # view to extract and view data points associated with those selections
    # Use the "u" character to toggle between "inspect modes" on the parallel
    # coordinates view (i.e. between selecting data and manipulating axes)
    # Note that no points will show up inside of the 3d box outline until you
    # select some lines/curves in the parallel coordinates view

    import vtk

    # Generate an image data set with multiple attribute arrays to probe and view
    rt = vtk.vtkRTAnalyticSource()
    rt.SetWholeExtent(-3, 3, -3, 3, -3, 3)
    grad = vtk.vtkImageGradient()
    grad.SetDimensionality(3)
    grad.SetInputConnection(rt.GetOutputPort())
    brown = vtk.vtkBrownianPoints()
    brown.SetMinimumSpeed(0.5)
    brown.SetMaximumSpeed(1.0)
    brown.SetInputConnection(grad.GetOutputPort())
    elev = vtk.vtkElevationFilter()
    elev.SetLowPoint(-3, -3, -3)
    elev.SetHighPoint(3, 3, 3)
    elev.SetInputConnection(brown.GetOutputPort())

    # Updating here because I will need to probe scalar ranges before
    # the render window updates the pipeline
    elev.Update()

    # Set up parallel coordinates representation to be used in View
    rep = vtk.vtkParallelCoordinatesRepresentation()
    if vtk.VTK_MAJOR_VERSION <= 5:
        rep.SetInput(elev.GetOutput())
    else:
        rep.SetInputConnection(elev.GetOutputPort())
    rep.SetInputArrayToProcess(0, 0, 0, 0, 'RTDataGradient')
    rep.SetInputArrayToProcess(1, 0, 0, 0, 'RTData')
    rep.SetInputArrayToProcess(2, 0, 0, 0, 'Elevation')
    rep.SetInputArrayToProcess(3, 0, 0, 0, 'BrownianVectors')
    rep.SetUseCurves(0)  # set to 1 to use smooth curves
    rep.SetLineOpacity(0.5)

    # Set up the Parallel Coordinates View and hook in representation
    view = vtk.vtkParallelCoordinatesView()
    view.SetRepresentation(rep)
    view.SetInspectMode(1)  # VTK_INSPECT_SELECT_DATA = 1
    view.SetBrushOperatorToReplace()
    view.SetBrushModeToLasso()

    # Create a annotation link to access selection in parallel coordinates view
    annotationLink = vtk.vtkAnnotationLink()
    # If you don't set the FieldType explicitly it ends up as UNKNOWN
    # (as of 21 Feb 2010)
    # See vtkSelectionNode doc for field and content type enum values
    annotationLink.GetCurrentSelection().GetNode(0).SetFieldType(1)  # Point
    annotationLink.GetCurrentSelection().GetNode(0).SetContentType(4)  # Indices
    # Update before passing annotationLink to vtkExtractSelection
    annotationLink.Update()
    # Connect the annotation link to the parallel coordinates representation
    rep.SetAnnotationLink(annotationLink)

    # Extract portion of data corresponding to parallel coordinates selection
    extract = vtk.vtkExtractSelection()
    if vtk.VTK_MAJOR_VERSION <= 5:
        extract.SetInput(0, elev.GetOutput())
        extract.SetInput(1, annotationLink.GetOutputDataObject(2))
    else:
        extract.SetInputConnection(0, elev.GetOutputPort())
        extract.SetInputConnection(1, annotationLink.GetOutputPort(2))

    def UpdateRenderWindows(obj, event):

        # Handle updating of RenderWindow since it's not a "View"
        # and so not covered by vtkViewUpdater
        # ren.ResetCamera()
        renWin.Render()

    # Set up callback to update 3d render window when selections are changed in
    # parallel coordinates view
    annotationLink.AddObserver("AnnotationChangedEvent", UpdateRenderWindows)

    def ToggleInspectors(obj, event):

        if (view.GetInspectMode() == 0):
            view.SetInspectMode(1)
        else:
            view.SetInspectMode(0)

    # Set up callback to toggle between inspect modes (manip axes & select data)
    view.GetInteractor().AddObserver("UserEvent", ToggleInspectors)

    # 3D outline of image data bounds
    outline = vtk.vtkOutlineFilter()
    outline.SetInputConnection(elev.GetOutputPort())
    outlineMapper = vtk.vtkPolyDataMapper()
    outlineMapper.SetInputConnection(outline.GetOutputPort())
    outlineActor = vtk.vtkActor()
    outlineActor.SetMapper(outlineMapper)

    # Build the lookup table for the 3d data scalar colors (brown to white)
    lut = vtk.vtkLookupTable()
    lut.SetTableRange(0, 256)
    lut.SetHueRange(0.1, 0.1)
    lut.SetSaturationRange(1.0, 0.1)
    lut.SetValueRange(0.4, 1.0)
    lut.Build()

    # Set up the 3d rendering parameters
    # of the image data which is selected in parallel coordinates
    coloring_by = 'Elevation'
    dataMapper = vtk.vtkDataSetMapper()
    dataMapper.SetInputConnection(extract.GetOutputPort())
    dataMapper.SetScalarModeToUsePointFieldData()
    dataMapper.SetColorModeToMapScalars()
    data = elev.GetOutputDataObject(0).GetPointData()
    dataMapper.ScalarVisibilityOn()
    dataMapper.SetScalarRange(data.GetArray(coloring_by).GetRange())
    dataMapper.SetLookupTable(lut)
    dataMapper.SelectColorArray(coloring_by)
    dataActor = vtk.vtkActor()
    dataActor.SetMapper(dataMapper)
    dataActor.GetProperty().SetRepresentationToPoints()
    dataActor.GetProperty().SetPointSize(10)

    # Set up the 3d render window and add both actors
    ren = vtk.vtkRenderer()
    ren.AddActor(outlineActor)
    ren.AddActor(dataActor)
    renWin = vtk.vtkRenderWindow()
    renWin.AddRenderer(ren)
    iren = vtk.vtkRenderWindowInteractor()
    iren.SetRenderWindow(renWin)
    ren.ResetCamera()
    renWin.Render()

    # Finalize parallel coordinates view and start interaction event loop
    view.GetRenderWindow().SetSize(600, 300)
    view.ResetCamera()
    view.Render()
    view.GetInteractor().Start()