#
#
def AveragePointToCellData(block,point_variable):
   #
   # Simple averaging of value at all nodes in element
   # like a simple PointDataToCellData filter
   numCells = block.GetNumberOfCells()
   elem_variable=zeros( (numCells,1) )
   #
   for element in range (numCells):
      # Initialize element variables
      elem_variable[element]=0.0
      cell=block.GetCell(element)
      numElemPts=cell.GetNumberOfPoints()
      # loop over pts and accumulate - divide by numPts for average
      for pt in range(numElemPts):
          pointID=cell.GetPointId(pt)
          #print pointID
          elem_variable[element]=elem_variable[element]+point_variable[pointID]
      elem_variable[element]=elem_variable[element]/numElemPts
      #print elem_variable[element]
   return elem_variable

#
def calc_element_angles(block):
   #
   # Must be done separately because of unique angle averaging problem at 180degrees
   # If average angles of 180 and -178, will get angle of 1 and we desire -179
   #
   # check if angles already exist
   if check_elem_variable_exists(block,'Sector_Angle_undef'):
      el_angles=block.CellData['Sector_Angle_undef']
      return el_angles
   #
   # Didn't find angles so: 
   # Get Node angles and average at each cell 
   # Undeformed Sector Angles (degrees about Y-axis, 0=FP)
   node_angles=calc_node_angles(block)
   #   
   #All nodes now have angles -  average and assign to elements
   # declare new variable arrays
   numCells = block.GetNumberOfCells()
   el_angles=zeros( (numCells,1) )
   #
   for element in range (numCells):
      cell=block.GetCell(element)
      numElemPts=cell.GetNumberOfPoints()
      # flags to detect border sectors with both positive and negative angles
      sector_angle_pos=0
      sector_angle_neg=0
      # Initialize element variables
      el_angles[element]=0.0
      # loop over pts and accumulate - divide by numPts for average
      for pt in range(numElemPts):
          pointID=cell.GetPointId(pt)
          #print pointID
          el_angles[element]=el_angles[element]+node_angles[pointID]
          if node_angles[pointID]>=0:
             sector_angle_pos=1
          else:
             sector_angle_neg=1
          #print el_angles[element]
      # detect "boundary" sectors with + and - angles and treat specially
      # sector between 180 and -178 deg would get +1deg from averaging
      # boundary sectors are always negative
      if (sector_angle_pos and sector_angle_neg):
         el_angles[element]=0.0
         for pt in range(numElemPts):
            pointID=cell.GetPointId(pt)
            el_angles[element]=el_angles[element]-abs(node_angles[pointID])
      el_angles[element]=el_angles[element]/numElemPts
      #print el_angles[element]
   return el_angles