issues: 376154741

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
376154741 MDU6SXNzdWUzNzYxNTQ3NDE= 2531 DataArray.rolling() does not preserve chunksizes in some cases 102827 closed 0     2 2018-10-31T20:50:33Z 2021-03-26T19:50:49Z 2021-03-26T19:50:49Z CONTRIBUTOR      

This issue was found and discussed in the related issue #2514

I open a separate issue for clarity.

Code Sample, a copy-pastable example if possible

```python import pandas as pd import numpy as np import xarray as xr

t = pd.date_range(start='2018-01-01', end='2018-02-01', freq='H') bar = np.sin(np.arange(len(t))) baz = np.cos(np.arange(len(t)))

da_test = xr.DataArray(data=np.stack([bar, baz]), coords={'time': t, 'sensor': ['one', 'two']}, dims=('sensor', 'time'))

print(da_test.chunk({'time': 100}).rolling(time=60).mean().chunks)

print(da_test.chunk({'time': 100}).rolling(time=60).count().chunks) Output for mean: ((2,), (745,)) Output for count: ((2,), (100, 100, 100, 100, 100, 100, 100, 45)) Desired Output: ((2,), (100, 100, 100, 100, 100, 100, 100, 45)) ```

Problem description

DataArray.rolling() does not preserve the chunksizes, apparently depending on the applied method.

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 2.7.15.final.0 python-bits: 64 OS: Darwin OS-release: 16.7.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: de_DE.UTF-8 LOCALE: None.None xarray: 0.10.9 pandas: 0.23.3 numpy: 1.13.3 scipy: 1.0.0 netCDF4: 1.4.1 h5netcdf: 0.5.0 h5py: 2.8.0 Nio: None zarr: None cftime: 1.0.1 PseudonetCDF: None rasterio: None iris: None bottleneck: 1.2.1 cyordereddict: 1.0.0 dask: 0.19.4 distributed: 1.23.3 matplotlib: 2.2.2 cartopy: 0.16.0 seaborn: 0.8.1 setuptools: 38.5.2 pip: 9.0.1 conda: 4.5.11 pytest: 3.4.2 IPython: 5.5.0 sphinx: None 
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   completed 13221727 issue

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