Bugfix lon_bounds returning range > 360 degrees (#859)

* Bugfix coordinates.lon_bounds for edge case returning >360 range

See issue #858

* lon_bounds: refactor

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Co-authored-by: Thomas Vogt <[email protected]>

Author: ChrisFairless

climada/util/coordinates.py

@@ -200,6 +200,7 @@ def lon_bounds(lon, buffer=0.0):
     if lon_diff_max < 2:
         # since the largest gap is comparably small, enforce the [-180, 180] value range
         gap_max = lon_diff.size - 1
+        lon_diff_max = lon_diff[gap_max]
     if lon_diff_max <= 2 * buffer:
         # avoid (-1, 359) and similar equivalent outputs for bounds covering the full circle
         lon_min, lon_max = (-180, 180)

climada/util/test/test_coordinates.py

@@ -265,6 +265,12 @@ def test_latlon_bounds(self):
         bounds = u_coord.latlon_bounds(lat, lon, buffer=1)
         self.assertEqual(bounds, (-180, -90, 180, 90))
 
+        # edge with values closer to the antimeridian than buffers and global coverage
+        lon = np.concatenate([[-179.99], np.arange(-179.7, 179.9, 0.2), [179.99]])
+        lat = np.zeros_like(lon)
+        bounds = u_coord.latlon_bounds(lat, lon, buffer=0.1)
+        self.assertEqual(bounds, (-180, -0.1, 180, 0.1))
+
     def test_toggle_extent_bounds(self):
         """Test the conversion between 'extent' and 'bounds'"""
         self.assertEqual(u_coord.toggle_extent_bounds((0, -1, 1, 3)), (0, 1, -1, 3))