使用min_periods和reduce时，xarray滚动与熊猫不匹配

Question

我正在对具有特定min_periods的滚动窗口应用自定义函数。 pandas..rolling.apply的输出符合我的期望；但是，xarray..rolling.reduce的输出似乎没有考虑min_periods。

MWE：

import numpy as np
import xarray

def custom(x, axis=0):
    return np.mean(x, axis)

d = pd.DataFrame(np.random.rand(100,3))
r = d.rolling(10, min_periods=5).apply(custom)
print(r.iloc[0:10,:])

xd = d.to_xarray().to_array()
r = xd.rolling(index=10, min_periods=5).reduce(custom)
print(r[:,0:10])
r = xd.rolling(index=10, min_periods=1).reduce(custom)
print(r[:,0:10])

输出：

          0         1         2
0       NaN       NaN       NaN
1       NaN       NaN       NaN
2       NaN       NaN       NaN
3       NaN       NaN       NaN
4  0.632168  0.523669  0.543643
5  0.558694  0.565781  0.481204
6  0.559343  0.541787  0.415490
7  0.613457  0.554888  0.398999
8  0.579552  0.496799  0.397681
9  0.562591  0.525096  0.416461
<xarray.DataArray (variable: 3, index: 10)>
array([[     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.562591],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.525096],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.416461]])
Coordinates:
  * index     (index) int64 0 1 2 3 4 5 6 7 8 9
  * variable  (variable) int64 0 1 2
<xarray.DataArray (variable: 3, index: 10)>
array([[     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.562591],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.525096],
       [     nan,      nan,      nan,      nan,      nan,      nan,      nan,
             nan,      nan, 0.416461]])
Coordinates:
  * index     (index) int64 0 1 2 3 4 5 6 7 8 9
  * variable  (variable) int64 0 1 2