Fix #451 and improve tests for downsampling

geoutils/raster/raster.py

@@ -549,7 +549,10 @@ def count(self) -> int:
     def height(self) -> int:
         """Height of the raster in pixels."""
         if not self.is_loaded:
-            return self._disk_shape[1]  # type: ignore
+            if self._out_shape is not None:
+                return self._out_shape[0]
+            else:
+                return self._disk_shape[1]  # type: ignore
         else:
             # If the raster is single-band
             if len(self.data.shape) == 2:
@@ -562,7 +565,10 @@ def height(self) -> int:
     def width(self) -> int:
         """Width of the raster in pixels."""
         if not self.is_loaded:
-            return self._disk_shape[2]  # type: ignore
+            if self._out_shape is not None:
+                return self._out_shape[1]
+            else:
+                return self._disk_shape[2]  # type: ignore
         else:
             # If the raster is single-band
             if len(self.data.shape) == 2:

tests/test_raster.py

@@ -611,33 +611,72 @@ def test_get_nanarray(self, example: str) -> None:
         mask = ~mask
         assert rst.raster_equal(rst_copy)
 
-    def test_downsampling(self) -> None:
+    @pytest.mark.parametrize("example", [aster_dem_path, landsat_b4_path, landsat_rgb_path])  # type: ignore
+    def test_downsampling(self, example: str) -> None:
         """
-        Check that self.data is correct when using downsampling
+        Check that self metadata are correctly updated when using downsampling
         """
-        # Test single band
-        r = gu.Raster(self.landsat_b4_path, downsample=4)
-        assert r.data.shape == (164, 200)
-        assert r.height == 164
-        assert r.width == 200
-
-        # Test multiple band
-        r = gu.Raster(self.landsat_rgb_path, downsample=2)
-        assert r.data.shape == (3, 328, 400)
-
-        # Test that xy2ij are consistent with new image
-        # Upper left
-        assert r.xy2ij(r.bounds.left, r.bounds.top) == (0, 0)
-        # Upper right
-        assert r.xy2ij(r.bounds.right + r.res[0], r.bounds.top) == (0, r.width + 1)
-        # Bottom right
-        assert r.xy2ij(r.bounds.right + r.res[0], r.bounds.bottom) == (r.height, r.width + 1)
-        # One pixel right and down
-        assert r.xy2ij(r.bounds.left + r.res[0], r.bounds.top - r.res[1]) == (1, 1)
-
-        # Check that error is raised when downsampling value is not valid
+        # Load raster at full resolution
+        rst_orig = gu.Raster(example)
+        bounds_orig = rst_orig.bounds
+
+        # -- Tries various downsampling factors to ensure rounding is needed in at least one case --
+        for down_fact in np.arange(2, 8):
+            rst_down = gu.Raster(example, downsample=int(down_fact))
+
+            # - Check that output resolution is as intended -
+            assert rst_down.res[0] == rst_orig.res[0] * down_fact
+            assert rst_down.res[1] == rst_orig.res[1] * down_fact
+
+            # - Check that downsampled width and height are as intended -
+            # Due to rounding, width/height can be up to 1 pixel larger than unrounded value
+            assert abs(rst_down.width - rst_orig.width / down_fact) < 1
+            assert abs(rst_down.height - rst_orig.height / down_fact) < 1
+            assert rst_down.shape == (rst_down.height, rst_down.width)
+
+            # - Check that bounds are updated accordingly -
+            # left/top bounds should be the same, right/bottom should be rounded to nearest pixel
+            bounds_down = rst_down.bounds
+            assert bounds_down.left == bounds_orig.left
+            assert bounds_down.top == bounds_orig.top
+            assert abs(bounds_down.right - bounds_orig.right) < rst_down.res[0]
+            assert abs(bounds_down.bottom - bounds_orig.bottom) < rst_down.res[1]
+
+            # - Check that metadata are consistent, with/out loading data -
+            assert not rst_down.is_loaded
+            width_unload = rst_down.width
+            height_unload = rst_down.height
+            bounds_unload = rst_down.bounds
+            rst_down.load()
+            width_load = rst_down.width
+            height_load = rst_down.height
+            bounds_load = rst_down.bounds
+            assert width_load == width_unload
+            assert height_load == height_unload
+            assert bounds_load == bounds_unload
+
+            # - Test that xy2ij are consistent with new image -
+            # Upper left
+            assert rst_down.xy2ij(rst_down.bounds.left, rst_down.bounds.top) == (0, 0)
+            # Upper right
+            assert rst_down.xy2ij(rst_down.bounds.right + rst_down.res[0], rst_down.bounds.top) == (
+                0,
+                rst_down.width + 1,
+            )
+            # Bottom right
+            assert rst_down.xy2ij(rst_down.bounds.right + rst_down.res[0], rst_down.bounds.bottom) == (
+                rst_down.height,
+                rst_down.width + 1,
+            )
+            # One pixel right and down
+            assert rst_down.xy2ij(rst_down.bounds.left + rst_down.res[0], rst_down.bounds.top - rst_down.res[1]) == (
+                1,
+                1,
+            )
+
+        # -- Check that error is raised when downsampling value is not valid --
         with pytest.raises(TypeError, match="downsample must be of type int or float."):
-            gu.Raster(self.landsat_b4_path, downsample=[1, 1])  # type: ignore
+            gu.Raster(example, downsample=[1, 1])  # type: ignore
 
     def test_add_sub(self) -> None:
         """