BUG: PeriodArray comparisons inconsistent with Period comparisons (#30722)

Author: jbrockmendel

doc/source/whatsnew/v1.0.0.rst

@@ -837,6 +837,7 @@ Datetimelike
 - Bug in :class:`DatetimeArray`, :class:`TimedeltaArray`, and :class:`PeriodArray` where inplace addition and subtraction did not actually operate inplace (:issue:`24115`)
 - Bug in :func:`pandas.to_datetime` when called with ``Series`` storing ``IntegerArray`` raising ``TypeError`` instead of returning ``Series`` (:issue:`30050`)
 - Bug in :func:`date_range` with custom business hours as ``freq`` and given number of ``periods`` (:issue:`30593`)
+- Bug in :class:`PeriodIndex` comparisons with incorrectly casting integers to :class:`Period` objects, inconsistent with the :class:`Period` comparison behavior (:issue:`30722`)
 
 Timedelta
 ^^^^^^^^^

pandas/core/arrays/period.py

@@ -73,19 +73,13 @@ def _period_array_cmp(cls, op):
 
     @unpack_zerodim_and_defer(opname)
     def wrapper(self, other):
-        ordinal_op = getattr(self.asi8, opname)
 
         if isinstance(other, str):
             try:
                 other = self._scalar_from_string(other)
             except ValueError:
                 # string that can't be parsed as Period
                 return invalid_comparison(self, other, op)
-        elif isinstance(other, int):
-            # TODO: sure we want to allow this?  we dont for DTA/TDA
-            #  2 tests rely on this
-            other = Period(other, freq=self.freq)
-            result = ordinal_op(other.ordinal)
 
         if isinstance(other, self._recognized_scalars) or other is NaT:
             other = self._scalar_type(other)

pandas/tests/arithmetic/test_period.py

@@ -127,14 +127,42 @@ def test_compare_object_dtype(self, box_with_array, other_box):
 class TestPeriodIndexComparisons:
     # TODO: parameterize over boxes
 
-    @pytest.mark.parametrize("other", ["2017", 2017])
+    @pytest.mark.parametrize("other", ["2017", pd.Period("2017", freq="D")])
     def test_eq(self, other):
         idx = PeriodIndex(["2017", "2017", "2018"], freq="D")
         expected = np.array([True, True, False])
         result = idx == other
 
         tm.assert_numpy_array_equal(result, expected)
 
+    @pytest.mark.parametrize(
+        "other",
+        [
+            2017,
+            [2017, 2017, 2017],
+            np.array([2017, 2017, 2017]),
+            np.array([2017, 2017, 2017], dtype=object),
+            pd.Index([2017, 2017, 2017]),
+        ],
+    )
+    def test_eq_integer_disallowed(self, other):
+        # match Period semantics by not treating integers as Periods
+
+        idx = PeriodIndex(["2017", "2017", "2018"], freq="D")
+        expected = np.array([False, False, False])
+        result = idx == other
+
+        tm.assert_numpy_array_equal(result, expected)
+
+        with pytest.raises(TypeError):
+            idx < other
+        with pytest.raises(TypeError):
+            idx > other
+        with pytest.raises(TypeError):
+            idx <= other
+        with pytest.raises(TypeError):
+            idx >= other
+
     def test_pi_cmp_period(self):
         idx = period_range("2007-01", periods=20, freq="M")
 

pandas/tests/indexes/period/test_period.py

@@ -462,7 +462,7 @@ def test_index_duplicate_periods(self):
         ts = Series(np.random.randn(len(idx)), index=idx)
 
         result = ts[2007]
-        expected = ts[idx == 2007]
+        expected = ts[idx == "2007"]
         tm.assert_series_equal(result, expected)
 
     def test_index_unique(self):