fix raise of TypeError when subtracting timedelta array

closes pandas-dev#21980

doc/source/whatsnew/v0.24.0.txt

@@ -441,7 +441,7 @@ Datetimelike
 Timedelta
 ^^^^^^^^^
 
--
+- Fixed bug where subtracting :class:`Timedelta` from an object-dtyped array would raise ``TypeError`` (:issue:`21980`)
 -
 -
 

pandas/_libs/tslibs/timedeltas.pyx

@@ -542,10 +542,12 @@ def _binary_op_method_timedeltalike(op, name):
 
         elif hasattr(other, 'dtype'):
             # nd-array like
-            if other.dtype.kind not in ['m', 'M']:
-                # raise rathering than letting numpy return wrong answer
+            if other.dtype.kind in ['m', 'M']:
+                return op(self.to_timedelta64(), other)
+            elif other.dtype.kind == 'O':
+                return np.array([op(self, x) for x in other])
+            else:
                 return NotImplemented
-            return op(self.to_timedelta64(), other)
 
         elif not _validate_ops_compat(other):
             return NotImplemented
@@ -929,7 +931,7 @@ cdef class _Timedelta(timedelta):
     def nanoseconds(self):
         """
         Return the number of nanoseconds (n), where 0 <= n < 1 microsecond.
-       
+
         Returns
         -------
         int

pandas/tests/scalar/timedelta/test_arithmetic.py

@@ -200,6 +200,92 @@ def test_td_rsub_numeric_raises(self):
         with pytest.raises(TypeError):
             2.0 - td
 
+    def test_td_sub_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        arr = np.array([Timestamp('20130101 9:01'),
+                        Timestamp('20121230 9:02')])
+        exp = np.array([Timestamp('20121231 9:01'),
+                        Timestamp('20121229 9:02')])
+        res = arr - pd.Timedelta('1D')
+        tm.assert_numpy_array_equal(res, exp)
+
+    def test_td_sub_mixed_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        now = pd.Timestamp.now()
+        arr = np.array([now,
+                        pd.Timedelta('1D')])
+        exp = np.array([now - pd.Timedelta('1D'),
+                        pd.Timedelta('0D')])
+        res = arr - pd.Timedelta('1D')
+        tm.assert_numpy_array_equal(res, exp)
+
+    def test_td_sub_mixed_most_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        now = pd.Timestamp.now()
+        arr = np.array([now,
+                        pd.Timedelta('1D'),
+                        np.timedelta64(2, 'h')])
+        exp = np.array([now - pd.Timedelta('1D'),
+                        pd.Timedelta('0D'),
+                        np.timedelta64(2, 'h') - pd.Timedelta('1D')])
+        res = arr - pd.Timedelta('1D')
+        tm.assert_numpy_array_equal(res, exp)
+
+    def test_td_rsub_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        arr = np.array([Timestamp('20130101 9:01'),
+                        Timestamp('20121230 9:02')])
+        with pytest.raises(TypeError):
+            # an timedelta - timestamp doesnt make sense
+            pd.Timedelta('1D') - arr
+
+    def test_td_rsub_mixed_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        now = pd.Timestamp.now()
+        arr = np.array([now,
+                        pd.Timedelta('1D')])
+        with pytest.raises(TypeError):
+            # an timedelta - timestamp doesnt make sense
+            pd.Timedelta('1D') - arr
+
+    def test_td_add_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        arr = np.array([Timestamp('20130101 9:01'),
+                        Timestamp('20121230 9:02')])
+        exp = np.array([Timestamp('20130102 9:01'),
+                        Timestamp('20121231 9:02')])
+        res = arr + pd.Timedelta('1D')
+        tm.assert_numpy_array_equal(res, exp)
+
+    def test_td_add_mixed_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        now = pd.Timestamp.now()
+        arr = np.array([now,
+                        pd.Timedelta('1D')])
+        exp = np.array([now + pd.Timedelta('1D'),
+                        pd.Timedelta('2D')])
+        res = arr + pd.Timedelta('1D')
+        tm.assert_numpy_array_equal(res, exp)
+
+    def test_td_radd_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        arr = np.array([Timestamp('20130101 9:01'),
+                        Timestamp('20121230 9:02')])
+        exp = np.array([Timestamp('20130102 9:01'),
+                        Timestamp('20121231 9:02')])
+        res = pd.Timedelta('1D') + arr
+        tm.assert_numpy_array_equal(res, exp)
+
+    def test_td_radd_mixed_timedeltalike_object_dtype_array(self):
+        # GH 21980
+        now = pd.Timestamp.now()
+        arr = np.array([now,
+                        pd.Timedelta('1D')])
+        exp = np.array([now + pd.Timedelta('1D'),
+                        pd.Timedelta('2D')])
+        res = pd.Timedelta('1D') + arr
+        tm.assert_numpy_array_equal(res, exp)
+
 
 class TestTimedeltaMultiplicationDivision(object):
     """
@@ -616,3 +702,35 @@ def test_rdivmod_invalid(self):
 
         with pytest.raises(TypeError):
             divmod(np.array([22, 24]), td)
+
+    def test_td_div_timedelta_timedeltalike_array(self):
+        # GH 21980
+        arr = np.array([Timestamp('20130101 9:01'),
+                        Timestamp('20121230 9:02')])
+
+        with pytest.raises(TypeError):
+            arr / pd.Timedelta('1D')
+
+    def test_td_rdiv_timedelta_mixed_timedeltalike_array(self):
+        # GH 21980
+        arr = np.array([pd.Timestamp.now(),
+                        pd.Timedelta('1D')])
+
+        with pytest.raises(TypeError):
+            pd.Timedelta('1D') / arr
+
+    def test_td_mult_timedelta_mixed_timedeltalike_array(self):
+        # GH 21980
+        arr = np.array([pd.Timestamp.now(),
+                        pd.Timedelta('1D')])
+
+        with pytest.raises(TypeError):
+            pd.Timedelta('1D') * arr
+
+    def test_td_rmult_timedelta_mixed_timedeltalike_array(self):
+        # GH 21980
+        arr = np.array([pd.Timestamp.now(),
+                        pd.Timedelta('1D')])
+
+        with pytest.raises(TypeError):
+            arr * pd.Timedelta('1D')