Fix unobserved categories dtype and normalize behavior + add tests for single grouper

Author: Lucas

doc/source/whatsnew/v1.5.0.rst

@@ -584,7 +584,7 @@ Categorical
 ^^^^^^^^^^^
 - Bug in :meth:`Categorical.view` not accepting integer dtypes (:issue:`25464`)
 - Bug in :meth:`CategoricalIndex.union` when the index's categories are integer-dtype and the index contains ``NaN`` values incorrectly raising instead of casting to ``float64`` (:issue:`45362`)
-- Bug in :meth:`DataFrameGroupBy.value_counts` includes non-observed categories of non-grouping columns regardless of ``observed`` (:issue:`46357`)
+- Bug in :meth:`.DataFrameGroupBy.value_counts` includes non-observed categories of non-grouping columns regardless of ``observed`` (:issue:`46357`)
 
 
 Datetimelike

pandas/core/groupby/generic.py

@@ -1780,7 +1780,7 @@ def value_counts(
                 and not grouping._observed
                 for grouping in groupings
             ):
-                levels_list = [ping.group_index for ping in groupings]
+                levels_list = [ping.result_index for ping in groupings]
                 multi_index, _ = MultiIndex.from_product(
                     levels_list, names=[ping.name for ping in groupings]
                 ).sortlevel()
@@ -1800,6 +1800,9 @@ def value_counts(
                 ).transform("sum")
                 result_series /= indexed_group_size
 
+                # Handle empty groups of non-observed categories
+                result_series = result_series.fillna(0.0)
+
             if sort:
                 # Sort the values and then resort by the main grouping
                 index_level = range(len(self.grouper.groupings))

pandas/tests/groupby/test_frame_value_counts.py

@@ -308,6 +308,156 @@ def test_data_frame_value_counts_dropna(
     tm.assert_series_equal(result_frame_groupby, expected)
 
 
+def _test_categorical_single_grouper(
+    education_df, as_index, observed, expected_index, normalize, expected_data
+):
+    # Test single categorical grouper when non-groupers are also categorical
+    education_df = education_df.copy().astype("category")
+
+    # Add non-observed grouping categories
+    education_df["country"] = education_df["country"].cat.add_categories(["ASIA"])
+
+    gp = education_df.groupby("country", as_index=as_index, observed=observed)
+    result = gp.value_counts(normalize=normalize)
+
+    expected_series = Series(
+        data=expected_data,
+        index=MultiIndex.from_tuples(
+            expected_index,
+            names=["country", "gender", "education"],
+        ),
+    )
+    for i in range(3):
+        index_level = CategoricalIndex(expected_series.index.levels[i])
+        if i == 0:
+            index_level = index_level.set_categories(
+                education_df["country"].cat.categories
+            )
+        expected_series.index = expected_series.index.set_levels(index_level, level=i)
+
+    if as_index:
+        tm.assert_series_equal(result, expected_series)
+    else:
+        expected = expected_series.reset_index(
+            name="proportion" if normalize else "count"
+        )
+        tm.assert_frame_equal(result, expected)
+
+
+@pytest.mark.parametrize("as_index", [True, False])
+@pytest.mark.parametrize(
+    "normalize, expected_data",
+    [
+        (False, np.array([2, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0], dtype=np.int64)),
+        (
+            True,
+            np.array([0.5, 0.25, 0.25, 0.0, 0.0, 0.0, 0.5, 0.5, 0.0, 0.0, 0.0, 0.0]),
+        ),
+    ],
+)
+def test_categorical_single_grouper_observed_true(
+    education_df, as_index, normalize, expected_data
+):
+    # GH#46357
+
+    expected_index = [
+        ("FR", "male", "low"),
+        ("FR", "female", "high"),
+        ("FR", "male", "medium"),
+        ("FR", "female", "low"),
+        ("FR", "female", "medium"),
+        ("FR", "male", "high"),
+        ("US", "female", "high"),
+        ("US", "male", "low"),
+        ("US", "female", "low"),
+        ("US", "female", "medium"),
+        ("US", "male", "high"),
+        ("US", "male", "medium"),
+    ]
+
+    _test_categorical_single_grouper(
+        education_df=education_df,
+        as_index=as_index,
+        observed=True,
+        expected_index=expected_index,
+        normalize=normalize,
+        expected_data=expected_data,
+    )
+
+
+@pytest.mark.parametrize("as_index", [True, False])
+@pytest.mark.parametrize(
+    "normalize, expected_data",
+    [
+        (
+            False,
+            np.array(
+                [2, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], dtype=np.int64
+            ),
+        ),
+        (
+            True,
+            np.array(
+                [
+                    0.5,
+                    0.25,
+                    0.25,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.5,
+                    0.5,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.0,
+                    0.0,
+                ]
+            ),
+        ),
+    ],
+)
+def test_categorical_single_grouper_observed_false(
+    education_df, as_index, normalize, expected_data
+):
+    # GH#46357
+
+    expected_index = [
+        ("FR", "male", "low"),
+        ("FR", "female", "high"),
+        ("FR", "male", "medium"),
+        ("FR", "female", "low"),
+        ("FR", "male", "high"),
+        ("FR", "female", "medium"),
+        ("US", "female", "high"),
+        ("US", "male", "low"),
+        ("US", "male", "medium"),
+        ("US", "male", "high"),
+        ("US", "female", "medium"),
+        ("US", "female", "low"),
+        ("ASIA", "male", "low"),
+        ("ASIA", "male", "high"),
+        ("ASIA", "female", "medium"),
+        ("ASIA", "female", "low"),
+        ("ASIA", "female", "high"),
+        ("ASIA", "male", "medium"),
+    ]
+
+    _test_categorical_single_grouper(
+        education_df=education_df,
+        as_index=as_index,
+        observed=False,
+        expected_index=expected_index,
+        normalize=normalize,
+        expected_data=expected_data,
+    )
+
+
 @pytest.mark.parametrize("as_index", [True, False])
 @pytest.mark.parametrize(
     "observed, expected_index",
@@ -348,15 +498,16 @@ def test_data_frame_value_counts_dropna(
         (
             True,
             # NaN values corresponds to non-observed groups
-            np.array(
-                [1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0, np.nan, np.nan]
-            ),
+            np.array([1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0, 0.0, 0.0]),
         ),
     ],
 )
-def test_categorical_groupers(
+def test_categorical_multiple_groupers(
     education_df, as_index, observed, expected_index, normalize, expected_data
 ):
+    # GH#46357
+
+    # Test multiple categorical groupers when non-groupers are non-categorical
     education_df = education_df.copy()
     education_df["country"] = education_df["country"].astype("category")
     education_df["education"] = education_df["education"].astype("category")
@@ -400,8 +551,10 @@ def test_categorical_groupers(
         ),
     ],
 )
-def test_categorical_values(education_df, as_index, observed, normalize, expected_data):
-    # Test non-observed categories are included in the result,
+def test_categorical_non_groupers(
+    education_df, as_index, observed, normalize, expected_data
+):
+    # GH#46357 Test non-observed categories are included in the result,
     # regardless of `observed`
     education_df = education_df.copy()
     education_df["gender"] = education_df["gender"].astype("category")