Merge pull request matplotlib#28862 from costaparas/improve-pie-chart-error

Improve pie chart error messages

Author: story645

lib/matplotlib/axes/_axes.py

@@ -3283,9 +3283,9 @@ def pie(self, x, explode=None, labels=None, colors=None,
         if explode is None:
             explode = [0] * len(x)
         if len(x) != len(labels):
-            raise ValueError("'label' must be of length 'x'")
+            raise ValueError(f"'labels' must be of length 'x', not {len(labels)}")
         if len(x) != len(explode):
-            raise ValueError("'explode' must be of length 'x'")
+            raise ValueError(f"'explode' must be of length 'x', not {len(explode)}")
         if colors is None:
             get_next_color = self._get_patches_for_fill.get_next_color
         else:
@@ -3298,7 +3298,7 @@ def get_next_color():
 
         _api.check_isinstance(Real, radius=radius, startangle=startangle)
         if radius <= 0:
-            raise ValueError(f'radius must be a positive number, not {radius}')
+            raise ValueError(f"'radius' must be a positive number, not {radius}")
 
         # Starting theta1 is the start fraction of the circle
         theta1 = startangle / 360

lib/matplotlib/tests/test_axes.py

@@ -6149,6 +6149,27 @@ def test_pie_get_negative_values():
         ax.pie([5, 5, -3], explode=[0, .1, .2])
 
 
+def test_pie_invalid_explode():
+    # Test ValueError raised when feeding short explode list to axes.pie
+    fig, ax = plt.subplots()
+    with pytest.raises(ValueError):
+        ax.pie([1, 2, 3], explode=[0.1, 0.1])
+
+
+def test_pie_invalid_labels():
+    # Test ValueError raised when feeding short labels list to axes.pie
+    fig, ax = plt.subplots()
+    with pytest.raises(ValueError):
+        ax.pie([1, 2, 3], labels=["One", "Two"])
+
+
+def test_pie_invalid_radius():
+    # Test ValueError raised when feeding negative radius to axes.pie
+    fig, ax = plt.subplots()
+    with pytest.raises(ValueError):
+        ax.pie([1, 2, 3], radius=-5)
+
+
 def test_normalize_kwarg_pie():
     fig, ax = plt.subplots()
     x = [0.3, 0.3, 0.1]