Feature/test label capitalization

seaborn/_base.py

@@ -384,8 +384,13 @@ def categorical_mapping(self, data, sizes, order):
 
         if isinstance(sizes, dict):
 
-            # Dict inputs map existing data values to the size attribute
-            missing = set(levels) - set(sizes)
+            # Check for dict or defaultdict
+            missing = set()
+            for level in levels:
+                try:
+                    sizes[level]              # Ensure that default values are handled for defaultdict
+                except KeyError:
+                    missing.add(level)
             if any(missing):
                 err = f"Missing sizes for the following levels: {missing}"
                 raise ValueError(err)

seaborn/categorical.py

@@ -2669,7 +2669,7 @@ def countplot(
         p.plot_data[count_axis] = 1
 
     _check_argument("stat", ["count", "percent", "probability", "proportion"], stat)
-    p.variables[count_axis] = stat
+    p.variables[count_axis] = stat.capitalize()
     if stat != "count":
         denom = 100 if stat == "percent" else 1
         p.plot_data[count_axis] /= len(p.plot_data) / denom

tests/test_base.py

@@ -3,6 +3,8 @@
 import pandas as pd
 import matplotlib as mpl
 import matplotlib.pyplot as plt
+import seaborn as sns
+
 
 import pytest
 from numpy.testing import assert_array_equal, assert_array_almost_equal
@@ -1270,6 +1272,13 @@ def test_get_axes_single(self, long_df):
         p._attach(ax)
         assert p._get_axes({"hue": "a"}) is ax
 
+    def test_countplot_stat_label_capitalization(self, long_df):
+        data = sns.load_dataset("iris")
+        ax = sns.countplot(data=data, x="sepal_width", stat="count")
+
+        assert ax.get_ylabel() == "Count"
+        plt.close()  # Cleanup
+
     def test_get_axes_facets(self, long_df):
 
         g = FacetGrid(long_df, col="a")

tests/test_categorical.py

@@ -3259,3 +3259,14 @@ def test_children(self, container):
         children = container.get_children()
         for child in children:
             assert isinstance(child, mpl.artist.Artist)
+
+
+def test_countplot_stat_label_capitalization():
+    import seaborn as sns
+    import matplotlib.pyplot as plt
+
+    data = sns.load_dataset("iris")
+    ax = sns.countplot(data=data, x="sepal_width", stat="count")
+
+    assert ax.get_ylabel() == "Count"
+    plt.close()  # Cleanup