"return" considered outside the function

Question

For the class below, I'm getting this exception:

return probe.GetOutput().GetPointData().GetArray('ImageScalars')
SyntaxError: 'return' outside function

Why is Python considering "return" outside the function? Is it an indentation issue? Thanks.

def probeVolume(self,volumeNode,rulerNode):
  # get ruler endpoints coordinates in RAS 
    p0ras = rulerNode.GetPolyData().GetPoint(0)+(1,)
    p1ras = rulerNode.GetPolyData().GetPoint(1)+(1,)

  # Convert RAS to IJK coordinates of the vtkImageData
  ras2ijk = vtk.vtkMatrix4x4()
  volumeNode.GetRASToIJKMatrix(ras2ijk)
  p0ijk = [int(round(c)) for c in ras2ijk.MultiplyPoint(p0ras)[:3]]
  p1ijk = [int(round(c)) for c in ras2ijk.MultiplyPoint(p1ras)[:3]]

    # Create VTK line that will be used for sampling
  line = vtk.vtkLineSource()
  line.SetResolution(100)
  line.SetPoint1(p0ijk[0],p0ijk[1],p0ijk[2])
  line.SetPoint2(p1ijk[0],p1ijk[1],p1ijk[2])

    # Create VTK probe filter and sample the image
  probe = vtk.vtkProbeFilter()
  probe.SetInputConnection(line.GetOutputPort())
  probe.SetSourceData(volumeNode.GetImageData())
  probe.Update()

    # return VTK array 
  return probe.GetOutput().GetPointData().GetArray('ImageScalars')

Answer 1

The problem is your inconsistency of indentation. Python depends on indentation to determine code blocks. To fix the problem, you'll need to indent all of the code in your probeVolume function by the same amount.

Answer 2

It is an indentation error. The first two lines of the function are double-indented.

Fix:

def probeVolume(self,volumeNode,rulerNode):
  # get ruler endpoints coordinates in RAS 
  p0ras = rulerNode.GetPolyData().GetPoint(0)+(1,)
  p1ras = rulerNode.GetPolyData().GetPoint(1)+(1,)

  # Convert RAS to IJK coordinates of the vtkImageData
  ras2ijk = vtk.vtkMatrix4x4()
  volumeNode.GetRASToIJKMatrix(ras2ijk)
  p0ijk = [int(round(c)) for c in ras2ijk.MultiplyPoint(p0ras)[:3]]
  p1ijk = [int(round(c)) for c in ras2ijk.MultiplyPoint(p1ras)[:3]]

    # Create VTK line that will be used for sampling
  line = vtk.vtkLineSource()
  line.SetResolution(100)
  line.SetPoint1(p0ijk[0],p0ijk[1],p0ijk[2])
  line.SetPoint2(p1ijk[0],p1ijk[1],p1ijk[2])

    # Create VTK probe filter and sample the image
  probe = vtk.vtkProbeFilter()
  probe.SetInputConnection(line.GetOutputPort())
  probe.SetSourceData(volumeNode.GetImageData())
  probe.Update()

    # return VTK array 
  return probe.GetOutput().GetPointData().GetArray('ImageScalars')

Answer 3

The first two lines of the function have 4 spaces from the function

def probeVolume(self,volumeNode,rulerNode):
  # get ruler endpoints coordinates in RAS 
    p0ras = rulerNode.GetPolyData().GetPoint(0)+(1,)
    p1ras = rulerNode.GetPolyData().GetPoint(1)+(1,)

I am not 100% sure if this is the issue , but try indenting the 3rd and 4th line with 2 spaces. Example -

def probeVolume(self,volumeNode,rulerNode):
  # get ruler endpoints coordinates in RAS 
  p0ras = rulerNode.GetPolyData().GetPoint(0)+(1,)
  p1ras = rulerNode.GetPolyData().GetPoint(1)+(1,)