Update tests for differently rounded center coordinates

pyxem/tests/utils/test_calibration_utils.py

@@ -90,16 +90,20 @@ def test_set_failure(self, calibration):
             calibration.detector(pixel_size=0.1, detector_distance=1)
         calibration.beam_energy = 200
         calibration.detector(pixel_size=0.1, detector_distance=1)
+        # The center, in pixel coordinates, is (4.5, 4.5)
+        # When using a detector, this gets rounded down to 4
+        assert calibration.center == [4, 4]
         calibration.detector(
             pixel_size=0.1, detector_distance=1, beam_energy=200, units="k_nm^-1"
         )
         assert calibration.flat_ewald is False
+        assert calibration.center == [4, 4]
         with pytest.raises(ValueError):
             calibration(scale=0.01)
         assert calibration.scale is None
         with pytest.raises(ValueError):
             calibration(center=(5, 5))
-        assert calibration.center == [5, 5]
+        assert calibration.center == [4, 4]
 
         with pytest.raises(ValueError):
             calibration.detector(pixel_size=0.1, detector_distance=1, units="nm^-1")

pyxem/utils/calibration.py

@@ -230,7 +230,7 @@ def detector(
             )
 
         if center is None:
-            center = [(ax.max() - ax.min()) / 2 for ax in self.axes]
+            center = [(ax.size - 1) / 2 for ax in self.axes]
 
         def translate_pixel_coords(px: np.ndarray) -> np.ndarray:
             coord = pixel_size * px
@@ -305,7 +305,7 @@ def pixel_extent(self):
         """
         if self.flat_ewald:
             extents = []
-            for ax, scale in zip(self.axes,  self.scale):
+            for ax, scale in zip(self.axes, self.scale):
                 left = ax - scale / 2
                 right = ax + scale / 2
                 extent = np.stack((left, right))