Add Grid.corner_coordinates attribute (#48)

.gitignore

@@ -116,12 +116,10 @@ ENV/
 env.bak/
 venv.bak/
 
-# Spyder project settings
+# IDE project settings
 .spyderproject
 .spyproject
-
-# Rope project settings
-.ropeproject
+.vscode/
 
 # mkdocs documentation
 /site

gridit/grid.py

@@ -111,6 +111,25 @@ def bounds(self):
         ymin = ymax - nrow * res
         return tuple(map(float, (xmin, ymin, xmax, ymax)))
 
+    @property
+    def corner_coords(self):
+        """Return 4 tuples of (x, y) coordinates to grid corners.
+
+        The order of the corners can be described with this figure:
+        (x0, y0)  (x3, y3)
+           +---------+
+           |         |
+           +---------+
+        (x1, y1)  (x2, y2)
+        """
+        xmin, ymin, xmax, ymax = self.bounds
+        return [
+            (xmin, ymax),
+            (xmin, ymin),
+            (xmax, ymin),
+            (xmax, ymax),
+        ]
+
     @property
     def transform(self):
         """Return Affine transform; requires affine."""

tests/test_grid.py

@@ -1,3 +1,5 @@
+import pickle
+
 import pytest
 
 from gridit import Grid
@@ -28,66 +30,87 @@ def test_grid_dict(grid_basic):
     assert grid_d["projection"] is None
 
 
-def test_grid_repr(grid_basic):
-    expected = "<Grid: resolution=10.0, shape=(20, 30), " "top_left=(1000.0, 2000.0) />"
-    assert repr(grid_basic) == expected
-    assert str(grid_basic) == expected
+@pytest.mark.parametrize(
+    "grid, expected_str",
+    [
+        pytest.param(
+            Grid(10, (20, 30), (1000.0, 2000.0)),
+            "<Grid: resolution=10.0, shape=(20, 30), top_left=(1000.0, 2000.0) />",
+            id="without projection",
+        ),
+        pytest.param(
+            Grid(10.0, (20, 30), (1000.0, 2000.0), "EPSG:2193"),
+            "<Grid: resolution=10.0, shape=(20, 30), top_left=(1000.0, 2000.0) />",
+            id="with projection",
+        ),
+    ],
+)
+def test_grid_repr(grid, expected_str):
+    assert repr(grid) == expected_str
+    assert str(grid) == expected_str
 
 
 def test_grid_eq_hash():
     grid1 = Grid(10, (20, 30), (1000.0, 2000.0))
     grid2 = Grid(10, (20, 30), (1001.0, 2000.0))
     grid3 = Grid(10, (20, 30), (1000.0, 2000.0), "EPSG:2193")
-    grid4 = Grid(10, (20, 30), (1000.0, 2000.0))
+    grid1r = Grid(10, (20, 30), (1000.0, 2000.0))
     assert grid1 != grid2
-    assert grid1 != grid3  # projection is different
-    assert grid1 == grid4
+    assert grid1 != grid3, "projection is different"
+    assert grid1 == grid1r
     hash1 = hash(grid1)
     hash2 = hash(grid2)
     hash3 = hash(grid3)
-    hash4 = hash(grid4)
+    hash1r = hash(grid1r)
     assert hash1 != hash2
-    assert hash1 != hash3  # projection is different
-    assert hash1 == hash4
+    assert hash1 != hash3, "projection is different"
+    assert hash1 == hash1r
 
 
 def test_grid_bounds(grid_basic):
     assert grid_basic.bounds == (1000.0, 1800.0, 1300.0, 2000.0)
 
 
+def test_grid_corner_coords(grid_basic):
+    assert grid_basic.corner_coords == [
+        (1000.0, 2000.0),
+        (1000.0, 1800.0),
+        (1300.0, 1800.0),
+        (1300.0, 2000.0),
+    ]
+
+
 @requires_pkg("affine")
 def test_grid_transform(grid_basic):
     from affine import Affine
 
     assert grid_basic.transform == Affine(10.0, 0.0, 1000.0, 0.0, -10.0, 2000.0)
 
 
-def test_pickle():
-    import pickle
-
-    # Without projection
-    grid = Grid(25.0, (36, 33), (1748725.0, 5449775.0))
-    expected_bytes = (
-        b"\x80\x04\x95c\x00\x00\x00\x00\x00\x00\x00\x8c\x0b"
-        b"gridit.grid\x94\x8c\x04Grid\x94\x93\x94)\x81\x94}\x94(\x8c\n"
-        b"resolution\x94G@9\x00\x00\x00\x00\x00\x00\x8c\x05"
-        b"shape\x94K$K!\x86\x94\x8c\x08"
-        b"top_left\x94GA:\xae\xf5\x00\x00\x00\x00GAT\xca\x0b\xc0\x00\x00\x00\x86"
-        b"\x94ub."
-    )
-    assert pickle.loads(expected_bytes) == grid, "failed loading previous serialization"
-    assert pickle.loads(pickle.dumps(grid)) == grid, "failed round-trip"
-
-    # With projection
-    grid = Grid(25.0, (36, 33), (1748725.0, 5449775.0), "EPSG:2193")
-    expected_bytes = (
-        b"\x80\x04\x95|\x00\x00\x00\x00\x00\x00\x00\x8c\x0b"
-        b"gridit.grid\x94\x8c\x04Grid\x94\x93\x94)\x81\x94}\x94(\x8c\n"
-        b"resolution\x94G@9\x00\x00\x00\x00\x00\x00\x8c\x05"
-        b"shape\x94K$K!\x86\x94\x8c\x08"
-        b"top_left\x94GA:\xae\xf5\x00\x00\x00\x00GAT\xca\x0b\xc0\x00\x00\x00\x86"
-        b"\x94\x8c\nprojection\x94\x8c\tEPSG:2193"
-        b"\x94ub."
-    )
+@pytest.mark.parametrize(
+    "grid, expected_bytes",
+    [
+        pytest.param(
+            Grid(25.0, (36, 33), (1748725.0, 5449775.0)),
+            b"\x80\x04\x95c\x00\x00\x00\x00\x00\x00\x00\x8c\x0b"
+            b"gridit.grid\x94\x8c\x04Grid\x94\x93\x94)\x81\x94}\x94(\x8c\n"
+            b"resolution\x94G@9\x00\x00\x00\x00\x00\x00\x8c\x05"
+            b"shape\x94K$K!\x86\x94\x8c\x08"
+            b"top_left\x94GA:\xae\xf5\x00\x00\x00\x00GAT\xca\x0b\xc0\x00\x00\x00\x86\x94ub.",
+            id="without projection",
+        ),
+        pytest.param(
+            Grid(25.0, (36, 33), (1748725.0, 5449775.0), projection="EPSG:2193"),
+            b"\x80\x04\x95|\x00\x00\x00\x00\x00\x00\x00\x8c\x0b"
+            b"gridit.grid\x94\x8c\x04Grid\x94\x93\x94)\x81\x94}\x94(\x8c\n"
+            b"resolution\x94G@9\x00\x00\x00\x00\x00\x00\x8c\x05"
+            b"shape\x94K$K!\x86\x94\x8c\x08"
+            b"top_left\x94GA:\xae\xf5\x00\x00\x00\x00GAT\xca\x0b\xc0\x00\x00\x00\x86"
+            b"\x94\x8c\nprojection\x94\x8c\tEPSG:2193\x94ub.",
+            id="with projection",
+        ),
+    ],
+)
+def test_pickle(grid, expected_bytes):
     assert pickle.loads(expected_bytes) == grid, "failed loading previous serialization"
     assert pickle.loads(pickle.dumps(grid)) == grid, "failed round-trip"