From f678977f470f0e752150d97afc4487d7c7647036 Mon Sep 17 00:00:00 2001
From: Michael Niklas <mick.niklas@gmail.com>
Date: Thu, 12 May 2022 17:11:56 +0200
Subject: [PATCH 1/2] re-add timedelta support for polyval

---
 xarray/core/computation.py       | 6 +++++-
 xarray/tests/test_computation.py | 6 ++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/xarray/core/computation.py b/xarray/core/computation.py
index 823cbe02560..8d450cceef9 100644
--- a/xarray/core/computation.py
+++ b/xarray/core/computation.py
@@ -1933,7 +1933,8 @@ def _ensure_numeric(data: T_Xarray) -> T_Xarray:
     from .dataset import Dataset
 
     def to_floatable(x: DataArray) -> DataArray:
-        if x.dtype.kind in "mM":
+        if x.dtype.kind == "M":
+            # datetimes
             return x.copy(
                 data=datetime_to_numeric(
                     x.data,
@@ -1941,6 +1942,9 @@ def to_floatable(x: DataArray) -> DataArray:
                     datetime_unit="ns",
                 ),
             )
+        elif x.dtype.kind == "m":
+            # timedeltas
+            return x.astype(float)
         return x
 
     if isinstance(data, Dataset):
diff --git a/xarray/tests/test_computation.py b/xarray/tests/test_computation.py
index 737ed82bc05..a3156214c08 100644
--- a/xarray/tests/test_computation.py
+++ b/xarray/tests/test_computation.py
@@ -2010,6 +2010,12 @@ def test_where_attrs() -> None:
             ),
             id="datetime",
         ),
+        pytest.param(
+            xr.DataArray(np.array([1000, 2000, 3000], dtype="timedelta64[ns]"), dims="x"),
+            xr.DataArray([0, 1], dims="degree", coords={"degree": [0, 1]}),
+            xr.DataArray([1000.0, 2000.0, 3000.0], dims="x"),
+            id="timedelta",
+        ),
     ],
 )
 def test_polyval(

From 01b8638ba6251c8987d512484c00960540bbea7a Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Thu, 12 May 2022 15:14:24 +0000
Subject: [PATCH 2/2] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 xarray/tests/test_computation.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xarray/tests/test_computation.py b/xarray/tests/test_computation.py
index a3156214c08..b8aa05c75e7 100644
--- a/xarray/tests/test_computation.py
+++ b/xarray/tests/test_computation.py
@@ -2011,7 +2011,9 @@ def test_where_attrs() -> None:
             id="datetime",
         ),
         pytest.param(
-            xr.DataArray(np.array([1000, 2000, 3000], dtype="timedelta64[ns]"), dims="x"),
+            xr.DataArray(
+                np.array([1000, 2000, 3000], dtype="timedelta64[ns]"), dims="x"
+            ),
             xr.DataArray([0, 1], dims="degree", coords={"degree": [0, 1]}),
             xr.DataArray([1000.0, 2000.0, 3000.0], dims="x"),
             id="timedelta",