support timedelta in Q_.init

CHANGES

@@ -7,6 +7,9 @@ Pint Changelog
 - Add `dim_sort` function to _formatter_helpers.
 - Add `dim_order` and `default_sort_func` properties to FullFormatter.
   (PR #1926, fixes Issue #1841)
+- `Quantity` now converts  `datetime.timedelta` objects to seconds or specified units when
+  initializing a `Quantity` with a `datetime.timedelta` value.
+  (PR #1978)
 
 
 0.23 (2023-12-08)

pint/compat.py

@@ -10,6 +10,7 @@
 
 from __future__ import annotations
 
+import datetime
 import math
 import sys
 from collections.abc import Callable, Iterable, Mapping
@@ -84,6 +85,7 @@ class BehaviorChangeWarning(UserWarning):
     import numpy as np
     from numpy import datetime64 as np_datetime64
     from numpy import ndarray
+    from numpy import timedelta64 as np_timedelta64
 
     HAS_NUMPY = True
     NUMPY_VER = np.__version__
@@ -136,6 +138,9 @@ class ndarray:
     class np_datetime64:
         pass
 
+    class np_timedelta64:
+        pass
+
     HAS_NUMPY = False
     NUMPY_VER = "0"
     NUMERIC_TYPES = (Number, Decimal)
@@ -293,6 +298,26 @@ def is_duck_array_type(cls: type) -> bool:
     )
 
 
+def is_timedelta(obj: Any) -> bool:
+    """Check if the object is a datetime object."""
+    return isinstance(obj, datetime.timedelta) or isinstance(obj, np_timedelta64)
+
+
+def is_timedelta_array(obj: Any) -> bool:
+    """Check if the object is a datetime array."""
+    if isinstance(obj, ndarray) and obj.dtype == np_timedelta64:
+        return True
+
+
+def to_seconds(obj: Any) -> float:
+    """Convert a timedelta object to seconds."""
+    if isinstance(obj, datetime.timedelta):
+        return obj.total_seconds()
+    elif isinstance(obj, np_timedelta64) or obj.dtype == np_timedelta64:
+        return obj.astype(float)
+    raise TypeError(f"Cannot convert {obj!r} to seconds.")
+
+
 def is_duck_array(obj: type) -> bool:
     """Check if an object represents a (non-Quantity) duck array type."""
     return is_duck_array_type(type(obj))

pint/facets/plain/quantity.py

@@ -30,8 +30,11 @@
     deprecated,
     eq,
     is_duck_array_type,
+    is_timedelta,
+    is_timedelta_array,
     is_upcast_type,
     np,
+    to_seconds,
     zero_or_nan,
 )
 from ...errors import DimensionalityError, OffsetUnitCalculusError, PintTypeError
@@ -203,7 +206,9 @@ def __new__(cls, value, units=None):
             return copy.copy(value)
 
         inst = SharedRegistryObject().__new__(cls)
-        if units is None:
+        if units is None and (is_timedelta(value) or is_timedelta_array(value)):
+            units = inst.UnitsContainer({"s": 1})
+        elif units is None:
             units = inst.UnitsContainer()
         else:
             if isinstance(units, (UnitsContainer, UnitDefinition)):
@@ -223,6 +228,11 @@ def __new__(cls, value, units=None):
                     "units must be of type str, PlainQuantity or "
                     "UnitsContainer; not {}.".format(type(units))
                 )
+        if is_timedelta(value) or is_timedelta_array(value):
+            inst._magnitude = to_seconds(value)
+            inst._units = inst.UnitsContainer({"s": 1})
+            return inst.to(units)
+
         if isinstance(value, cls):
             magnitude = value.to(units)._magnitude
         else:

pint/testsuite/test_quantity.py

@@ -1884,6 +1884,28 @@ def test_iadd_isub(self):
         with pytest.raises(DimensionalityError):
             after -= d
 
+    def test_init_quantity(self):
+        # 608
+        td = datetime.timedelta(seconds=3)
+        assert self.Q_(td) == 3 * self.ureg.second
+        q_hours = self.Q_(td, "hours")
+        assert q_hours == 3 * self.ureg.second
+        assert q_hours.units == self.ureg.hour
+
+    @helpers.requires_numpy
+    def test_init_quantity_np(self):
+        td = np.timedelta64(3, "s")
+        assert self.Q_(td) == 3 * self.ureg.second
+        q_hours = self.Q_(td, "hours")
+        assert q_hours == 3 * self.ureg.second
+        assert q_hours.units == self.ureg.hour
+
+        td = np.array([3], dtype="timedelta64")
+        assert self.Q_(td) == np.array([3]) * self.ureg.second
+        q_hours = self.Q_(td, "hours")
+        assert q_hours == np.array([3]) * self.ureg.second
+        assert q_hours.units == self.ureg.hour
+
 
 # TODO: do not subclass from QuantityTestCase
 class TestCompareNeutral(QuantityTestCase):