Add center property to Interval and BoundingBox to simplify shape calculations (#263)

Author: stefmolin

src/data_morph/bounds/bounding_box.py

@@ -167,3 +167,15 @@ def range(self) -> Iterable[Number]:
             The range covered by the x and y bounds, respectively.
         """
         return self.x_bounds.range, self.y_bounds.range
+
+    @property
+    def center(self) -> Iterable[Number]:
+        """
+        Calculate the center of the bounding box.
+
+        Returns
+        -------
+        Iterable[numbers.Number]
+            The center of the x and y bounds, respectively.
+        """
+        return self.x_bounds.center, self.y_bounds.center

src/data_morph/bounds/interval.py

@@ -164,3 +164,15 @@ def range(self) -> Number:
             The range covered by the interval.
         """
         return abs(self._bounds[1] - self._bounds[0])
+
+    @property
+    def center(self) -> Number:
+        """
+        Calculate the center of the interval.
+
+        Returns
+        -------
+        numbers.Number
+            The center of the interval.
+        """
+        return sum(self) / 2

src/data_morph/shapes/points/club.py

@@ -29,18 +29,14 @@ class Club(PointCollection):
     """
 
     def __init__(self, dataset: Dataset) -> None:
-        x_bounds = dataset.data_bounds.x_bounds
-        y_bounds = dataset.data_bounds.y_bounds
-
-        x_shift = sum(x_bounds) / 2
-        y_shift = sum(y_bounds) / 2
-        scale_factor = min(x_bounds.range, y_bounds.range) / 75
+        scale_factor = min(*dataset.data_bounds.range) / 75
 
         x_lobes, y_lobes = self._get_lobes(scale_factor)
         x_stem, y_stem = self._get_stem(scale_factor)
 
-        xs = x_shift + np.concatenate(x_lobes + x_stem)
-        ys = y_shift + np.concatenate(y_lobes + y_stem)
+        x_center, y_center = dataset.data_bounds.center
+        xs = x_center + np.concatenate(x_lobes + x_stem)
+        ys = y_center + np.concatenate(y_lobes + y_stem)
 
         super().__init__(*np.stack([xs, ys], axis=1))
 

src/data_morph/shapes/points/heart.py

@@ -36,10 +36,7 @@ class Heart(PointCollection):
 
     def __init__(self, dataset: Dataset) -> None:
         x_bounds = dataset.data_bounds.x_bounds
-        y_bounds = dataset.data_bounds.y_bounds
-
-        x_shift = sum(x_bounds) / 2
-        y_shift = sum(y_bounds) / 2
+        x_shift, y_shift = dataset.data_bounds.center
 
         t = np.linspace(-3, 3, num=80)
 

src/data_morph/shapes/points/spade.py

@@ -31,10 +31,7 @@ class Spade(PointCollection):
 
     def __init__(self, dataset: Dataset) -> None:
         x_bounds = dataset.data_bounds.x_bounds
-        y_bounds = dataset.data_bounds.y_bounds
-
-        x_shift = sum(x_bounds) / 2
-        y_shift = sum(y_bounds) / 2
+        x_shift, y_shift = dataset.data_bounds.center
 
         # upside-down heart
         heart_points = self._get_inverted_heart(dataset, y_shift)

tests/bounds/test_bounding_box.py

@@ -205,3 +205,8 @@ def test_range(self):
         """Test that the range property is working."""
         bbox = BoundingBox([0, 10], [5, 10])
         assert bbox.range == (10, 5)
+
+    def test_center(self):
+        """Test that the center property is working."""
+        bbox = BoundingBox([0, 10], [5, 10])
+        assert bbox.center == (5, 7.5)

tests/bounds/test_interval.py

@@ -172,3 +172,18 @@ def test_range(self, limits, inclusive, expected):
         """Test that the range property is working."""
         bounds = Interval(limits, inclusive)
         assert bounds.range == expected
+
+    @pytest.mark.parametrize('inclusive', [True, False])
+    @pytest.mark.parametrize(
+        ('limits', 'expected'),
+        [
+            ([-10, -5], -7.5),
+            ([-1, 1], 0),
+            ([2, 100], 51),
+        ],
+        ids=str,
+    )
+    def test_center(self, limits, inclusive, expected):
+        """Test that the center property is working."""
+        bounds = Interval(limits, inclusive)
+        assert bounds.center == expected