BUG: PeriodIndex.searchsorted accepting invalid inputs (#30763)

Author: jbrockmendel

doc/source/whatsnew/v1.0.0.rst

@@ -937,6 +937,7 @@ Indexing
 - :meth:`Index.get_indexer_non_unique` could fail with `TypeError` in some cases, such as when searching for ints in a string index (:issue:`28257`)
 - Bug in :meth:`Float64Index.get_loc` incorrectly raising ``TypeError`` instead of ``KeyError`` (:issue:`29189`)
 - Bug in :meth:`Series.__setitem__` incorrectly assigning values with boolean indexer when the length of new data matches the number of ``True`` values and new data is not a ``Series`` or an ``np.array`` (:issue:`30567`)
+- Bug in indexing with a :class:`PeriodIndex` incorrectly accepting integers representing years, use e.g. ``ser.loc["2007"]`` instead of ``ser.loc[2007]`` (:issue:`30763`)
 
 Missing
 ^^^^^^^

pandas/core/generic.py

@@ -6972,8 +6972,7 @@ def asof(self, where, subset=None):
         if not is_list:
             start = self.index[0]
             if isinstance(self.index, PeriodIndex):
-                where = Period(where, freq=self.index.freq).ordinal
-                start = start.ordinal
+                where = Period(where, freq=self.index.freq)
 
             if where < start:
                 if not is_series:

pandas/core/indexes/period.py

@@ -469,17 +469,19 @@ def astype(self, dtype, copy=True, how="start"):
     @Substitution(klass="PeriodIndex")
     @Appender(_shared_docs["searchsorted"])
     def searchsorted(self, value, side="left", sorter=None):
-        if isinstance(value, Period):
-            if value.freq != self.freq:
-                raise raise_on_incompatible(self, value)
-            value = value.ordinal
+        if isinstance(value, Period) or value is NaT:
+            self._data._check_compatible_with(value)
         elif isinstance(value, str):
             try:
-                value = Period(value, freq=self.freq).ordinal
+                value = Period(value, freq=self.freq)
             except DateParseError:
                 raise KeyError(f"Cannot interpret '{value}' as period")
+        elif not isinstance(value, PeriodArray):
+            raise TypeError(
+                "PeriodIndex.searchsorted requires either a Period or PeriodArray"
+            )
 
-        return self._ndarray_values.searchsorted(value, side=side, sorter=sorter)
+        return self._data.searchsorted(value, side=side, sorter=sorter)
 
     @property
     def is_full(self) -> bool:
@@ -703,8 +705,7 @@ def _get_string_slice(self, key):
 
         t1, t2 = self._parsed_string_to_bounds(reso, parsed)
         return slice(
-            self.searchsorted(t1.ordinal, side="left"),
-            self.searchsorted(t2.ordinal, side="right"),
+            self.searchsorted(t1, side="left"), self.searchsorted(t2, side="right")
         )
 
     def _convert_tolerance(self, tolerance, target):

pandas/core/resample.py

@@ -1586,7 +1586,10 @@ def _get_period_bins(self, ax):
         rng += freq_mult
         # adjust bin edge indexes to account for base
         rng -= bin_shift
-        bins = memb.searchsorted(rng, side="left")
+
+        # Wrap in PeriodArray for PeriodArray.searchsorted
+        prng = type(memb._data)(rng, dtype=memb.dtype)
+        bins = memb.searchsorted(prng, side="left")
 
         if nat_count > 0:
             # NaT handling as in pandas._lib.lib.generate_bins_dt64()

pandas/tests/frame/methods/test_asof.py

@@ -1,7 +1,7 @@
 import numpy as np
 import pytest
 
-from pandas import DataFrame, Series, Timestamp, date_range, to_datetime
+from pandas import DataFrame, Period, Series, Timestamp, date_range, to_datetime
 import pandas._testing as tm
 
 
@@ -80,6 +80,12 @@ def test_missing(self, date_range_frame):
         )
         tm.assert_frame_equal(result, expected)
 
+        # Check that we handle PeriodIndex correctly, dont end up with
+        #  period.ordinal for series name
+        df = df.to_period("D")
+        result = df.asof("1989-12-31")
+        assert isinstance(result.name, Period)
+
     def test_all_nans(self, date_range_frame):
         # GH 15713
         # DataFrame is all nans

pandas/tests/indexes/period/test_period.py

@@ -451,7 +451,7 @@ def test_index_duplicate_periods(self):
         idx = PeriodIndex([2000, 2007, 2007, 2009, 2009], freq="A-JUN")
         ts = Series(np.random.randn(len(idx)), index=idx)
 
-        result = ts[2007]
+        result = ts["2007"]
         expected = ts[1:3]
         tm.assert_series_equal(result, expected)
         result[:] = 1
@@ -461,7 +461,7 @@ def test_index_duplicate_periods(self):
         idx = PeriodIndex([2000, 2007, 2007, 2009, 2007], freq="A-JUN")
         ts = Series(np.random.randn(len(idx)), index=idx)
 
-        result = ts[2007]
+        result = ts["2007"]
         expected = ts[idx == "2007"]
         tm.assert_series_equal(result, expected)
 

pandas/tests/indexes/period/test_tools.py

@@ -231,14 +231,43 @@ def test_searchsorted(self, freq):
         p2 = pd.Period("2014-01-04", freq=freq)
         assert pidx.searchsorted(p2) == 3
 
-        msg = "Input has different freq=H from PeriodIndex"
+        assert pidx.searchsorted(pd.NaT) == 0
+
+        msg = "Input has different freq=H from PeriodArray"
         with pytest.raises(IncompatibleFrequency, match=msg):
             pidx.searchsorted(pd.Period("2014-01-01", freq="H"))
 
-        msg = "Input has different freq=5D from PeriodIndex"
+        msg = "Input has different freq=5D from PeriodArray"
         with pytest.raises(IncompatibleFrequency, match=msg):
             pidx.searchsorted(pd.Period("2014-01-01", freq="5D"))
 
+    def test_searchsorted_invalid(self):
+        pidx = pd.PeriodIndex(
+            ["2014-01-01", "2014-01-02", "2014-01-03", "2014-01-04", "2014-01-05"],
+            freq="D",
+        )
+
+        other = np.array([0, 1], dtype=np.int64)
+
+        msg = "requires either a Period or PeriodArray"
+        with pytest.raises(TypeError, match=msg):
+            pidx.searchsorted(other)
+
+        with pytest.raises(TypeError, match=msg):
+            pidx.searchsorted(other.astype("timedelta64[ns]"))
+
+        with pytest.raises(TypeError, match=msg):
+            pidx.searchsorted(np.timedelta64(4))
+
+        with pytest.raises(TypeError, match=msg):
+            pidx.searchsorted(np.timedelta64("NaT", "ms"))
+
+        with pytest.raises(TypeError, match=msg):
+            pidx.searchsorted(np.datetime64(4, "ns"))
+
+        with pytest.raises(TypeError, match=msg):
+            pidx.searchsorted(np.datetime64("NaT", "ns"))
+
 
 class TestPeriodIndexConversion:
     def test_tolist(self):