docs: def make_data(self):
          """Return data of the field in a format that can be converted to JSON
          
          Returns:
            data (dict): A dictionary of dictionaries, such that for a given x, y pair,
              data[x][y] = {"dx": dx, "dy": dy}. Note that this is transposed from the
              matrix representation in DX and DY
          """
          X, Y, DX, DY = self._calc_partials()
          data = {}
          import pdb
          for x in self.xrange:
              data[x] = {}
              for y in self.yrange:
                  data[x][y] = {"dx": DX[y, x], "dy": DY[y, x]}
          return data