old_contents: import unittest
  
  import numpy as np
  
  from laserchicken import keys
  from laserchicken.feature_extractor import compute_features
  from laserchicken.test_tools import create_point_cloud, create_points_in_xy_grid
  from laserchicken.volume_specification import InfiniteCylinder
  
  
  class TestExtractSigmaZ(unittest.TestCase):
      def test_constantValues_result0(self):
          def z_constant(_, _):
              return 2
  
          assert_std_for_z_function_in_xy_grid(z_constant, 0)
  
      def test_checkered1sAnd0s_resultHalf(self):
          """Standard deviation of checker pattern of 0s and 1s should be 0.5"""
  
          def z_checkered(x, y):
              return ((x + y) % 2) + 2
  
          assert_std_for_z_function_in_xy_grid(z_checkered, 0.5)
  
      def test_checkered1sAnd0sPlusSkewed_resultHalf(self):
          """Standard deviation of checker pattern of 0s and 1s should be 0.5, adding a plane should not change that"""
  
          def z_checkered(x, y):
              return ((x + y) % 2) + 2 + x + y
  
          assert_std_for_z_function_in_xy_grid(z_checkered, 0.5)
  
  
  def assert_std_for_z_function_in_xy_grid(z_checkered, expected):
      """Assert that the standard deviation of z values in a grid of unit x and y"""
      n_points, points = create_points_in_xy_grid(z_checkered)
      point_cloud = create_point_cloud(points[:, 0], points[:, 1], points[:, 2])
      targets = create_point_cloud([0], [0], [0])
      compute_features(point_cloud, [range(n_points)], 0, targets, [
                       'sigma_z'], InfiniteCylinder(10))
      np.testing.assert_almost_equal(
          targets[keys.point]['sigma_z']['data'][0], expected)
  
  
  
  
new_contents: import unittest
  
  import numpy as np
  
  from laserchicken import keys
  from laserchicken.feature_extractor import compute_features
  from laserchicken.test_tools import create_point_cloud, create_points_in_xy_grid
  from laserchicken.volume_specification import InfiniteCylinder
  
  
  class TestExtractSigmaZ(unittest.TestCase):
      def test_constantValues_result0(self):
          def z_constant(x, y):
              return 2
  
          assert_std_for_z_function_in_xy_grid(z_constant, 0)
  
      def test_checkered1sAnd0s_resultHalf(self):
          """Standard deviation of checker pattern of 0s and 1s should be 0.5"""
  
          def z_checkered(x, y):
              return ((x + y) % 2) + 2
  
          assert_std_for_z_function_in_xy_grid(z_checkered, 0.5)
  
      def test_checkered1sAnd0sPlusSkewed_resultHalf(self):
          """Standard deviation of checker pattern of 0s and 1s should be 0.5, adding a plane should not change that"""
  
          def z_checkered(x, y):
              return ((x + y) % 2) + 2 + x + y
  
          assert_std_for_z_function_in_xy_grid(z_checkered, 0.5)
  
  
  def assert_std_for_z_function_in_xy_grid(z_checkered, expected):
      """Assert that the standard deviation of z values in a grid of unit x and y"""
      n_points, points = create_points_in_xy_grid(z_checkered)
      point_cloud = create_point_cloud(points[:, 0], points[:, 1], points[:, 2])
      targets = create_point_cloud([0], [0], [0])
      compute_features(point_cloud, [range(n_points)], 0, targets, [
                       'sigma_z'], InfiniteCylinder(10))
      np.testing.assert_almost_equal(
          targets[keys.point]['sigma_z']['data'][0], expected)
  
  
  
  
subject: fix variable name collision