Backport PR #36535: Regr/period range large value/issue 36430 (#36572)

Co-authored-by: nrebena <[email protected]>

Author: meeseeksmachine

doc/source/whatsnew/v1.1.3.rst

@@ -36,6 +36,7 @@ Fixed regressions
 - Fixed regression in :meth:`read_excel` with ``engine="odf"`` caused ``UnboundLocalError`` in some cases where cells had nested child nodes (:issue:`36122`,:issue:`35802`)
 - Fixed regression in :class:`DataFrame` and :class:`Series` comparisons between numeric arrays and strings (:issue:`35700`,:issue:`36377`)
 - Fixed regression when setting empty :class:`DataFrame` column to a :class:`Series` in preserving name of index in frame (:issue:`36527`)
+- Fixed regression in :class:`Period` incorrect value for ordinal over the maximum timestamp (:issue:`36430`)
 
 .. ---------------------------------------------------------------------------
 

pandas/_libs/tslibs/period.pyx

@@ -861,6 +861,7 @@ cdef int64_t get_time_nanos(int freq, int64_t unix_date, int64_t ordinal) nogil:
     """
     cdef:
         int64_t sub, factor
+        int64_t nanos_in_day = 24 * 3600 * 10**9
 
     freq = get_freq_group(freq)
 
@@ -886,7 +887,7 @@ cdef int64_t get_time_nanos(int freq, int64_t unix_date, int64_t ordinal) nogil:
         # We must have freq == FR_HR
         factor = 10**9 * 3600
 
-    sub = ordinal - unix_date * 24 * 3600 * 10**9 / factor
+    sub = ordinal - unix_date * (nanos_in_day / factor)
     return sub * factor
 
 

pandas/tests/scalar/period/test_period.py

@@ -486,6 +486,13 @@ def test_period_cons_combined(self):
         with pytest.raises(ValueError, match=msg):
             Period("2011-01", freq="1D1W")
 
+    @pytest.mark.parametrize("hour", range(24))
+    def test_period_large_ordinal(self, hour):
+        # Issue #36430
+        # Integer overflow for Period over the maximum timestamp
+        p = pd.Period(ordinal=2562048 + hour, freq="1H")
+        assert p.hour == hour
+
 
 class TestPeriodMethods:
     def test_round_trip(self):