docs: def extract_points(self, pid, points):
          """Extract values at certain points in the grid from a given parameter
          set. Cells are selected by interpolating the centroids of the cells
          towards the line using a "nearest" scheme.
  
          Note that data is only returned for the points provided. If you want to
          extract multiple data points along a line, defined by start and end
          point, use the **extract_along_line** function.
  
          Parameters
          ----------
          pid: int
              The parameter id to extract values from
          points: Nx2 numpy.ndarray
              (x, y) pairs
  
          Returns
          -------
          values: numpy.ndarray (n x 1)
              data values for extracted data points
          """
          xy = self.grid.get_element_centroids()
          data = self.parsets[pid]
  
          iobj = spi.NearestNDInterpolator(xy, data)
          values = iobj(points)
          return values