BUG: Timedelta from Tick offsets now behaves like keyword arguments (GH#62310)

Author: skalwaghe-56

doc/source/whatsnew/v3.0.0.rst

@@ -919,6 +919,7 @@ Timedelta
 ^^^^^^^^^
 - Accuracy improvement in :meth:`Timedelta.to_pytimedelta` to round microseconds consistently for large nanosecond based Timedelta (:issue:`57841`)
 - Bug in :class:`Timedelta` constructor failing to raise when passed an invalid keyword (:issue:`53801`)
+- Bug in :class:`Timedelta` when constructed from Tick offsets (e.g., ``Timedelta(offsets.Hour(1))``) that could produce incorrect results in arithmetic. Timedelta now handles Hour, Minute, and Second offsets consistently with keyword arguments (:issue:`62310`)
 - Bug in :meth:`DataFrame.cumsum` which was raising ``IndexError`` if dtype is ``timedelta64[ns]`` (:issue:`57956`)
 - Bug in multiplication operations with ``timedelta64`` dtype failing to raise ``TypeError`` when multiplying by ``bool`` objects or dtypes (:issue:`58054`)
 

pandas/_libs/tslibs/timedeltas.pyx

@@ -2012,6 +2012,8 @@ class Timedelta(_Timedelta):
                            "milliseconds", "microseconds", "nanoseconds"}
 
     def __new__(cls, object value=_no_input, unit=None, **kwargs):
+        cdef NPY_DATETIMEUNIT in_reso
+        cdef NPY_DATETIMEUNIT target_reso
         unsupported_kwargs = set(kwargs)
         unsupported_kwargs.difference_update(cls._req_any_kwargs_new)
         if unsupported_kwargs or (
@@ -2134,9 +2136,30 @@ class Timedelta(_Timedelta):
             return cls._from_value_and_reso(new_value, reso=new_reso)
 
         elif is_tick_object(value):
-            new_reso = get_supported_reso(value._creso)
-            new_value = delta_to_nanoseconds(value, reso=new_reso)
-            return cls._from_value_and_reso(new_value, reso=new_reso)
+            # GH#62310
+            # Handle Tick offsets
+            in_reso = value._creso
+
+            if in_reso == NPY_DATETIMEUNIT.NPY_FR_ns:
+                target_reso = NPY_DATETIMEUNIT.NPY_FR_ns
+            elif in_reso == NPY_DATETIMEUNIT.NPY_FR_us:
+                target_reso = NPY_DATETIMEUNIT.NPY_FR_us
+            elif in_reso == NPY_DATETIMEUNIT.NPY_FR_ms:
+                target_reso = NPY_DATETIMEUNIT.NPY_FR_ms
+            elif in_reso in (
+                NPY_DATETIMEUNIT.NPY_FR_s,
+                NPY_DATETIMEUNIT.NPY_FR_m,
+                NPY_DATETIMEUNIT.NPY_FR_h,
+            ):
+                target_reso = NPY_DATETIMEUNIT.NPY_FR_s
+            else:
+                raise ValueError(
+                    f"Value must be Timedelta, string, integer, float, timedelta "
+                    f"or convertible, not {type(value).__name__}"
+                )
+
+            new_value = delta_to_nanoseconds(value, reso=target_reso)
+            return cls._from_value_and_reso(new_value, reso=target_reso)
 
         elif is_integer_object(value) or is_float_object(value):
             # unit=None is de-facto 'ns'

pandas/tests/scalar/timedelta/test_constructors.py

@@ -13,6 +13,7 @@
     NaT,
     Timedelta,
     TimedeltaIndex,
+    Timestamp,
     offsets,
     to_timedelta,
 )
@@ -263,6 +264,36 @@ def test_from_tick_reso():
         Timedelta(tick)
 
 
+def test_tick_offset_arithmetic_consistency():
+    # GH#62310: Timedelta construction from Tick offset objects should
+    # behave consistently with Timedelta keyword arguments
+
+    # Construct Timedelta from Tick offset vs keyword argument
+    tick_td = Timedelta(offsets.Hour(1))
+    kwarg_td = Timedelta(hours=1)
+
+    # Both should represent the same duration
+    assert tick_td == kwarg_td
+    assert tick_td.value == kwarg_td.value
+
+    # Subtraction with Timestamp
+    ts = Timestamp("2020-01-01 02:00:00")
+    result1 = ts - tick_td
+    result2 = ts - kwarg_td
+    assert result1 == result2 == Timestamp("2020-01-01 01:00:00")
+
+    # Addition with Timestamp
+    ts2 = Timestamp("2020-01-01 00:00:00")
+    result3 = ts2 + tick_td
+    result4 = ts2 + kwarg_td
+    assert result3 == result4 == Timestamp("2020-01-01 01:00:00")
+
+    # Timedelta arithmetic
+    assert tick_td - kwarg_td == Timedelta(0)
+    assert kwarg_td - tick_td == Timedelta(0)
+    assert tick_td + kwarg_td == Timedelta(hours=2)
+
+
 def test_construction():
     expected = np.timedelta64(10, "D").astype("m8[ns]").view("i8")
     assert Timedelta(10, unit="D")._value == expected