issues: 363326726

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363326726 MDU6SXNzdWUzNjMzMjY3MjY= 2437 xarray potential inconstistencies with cftime 16655388 closed 0     16 2018-09-24T21:25:46Z 2021-06-22T17:01:35Z 2019-02-08T15:05:38Z NONE      

I am trying to use xarray with different types of calendars. I made a few tests and wonder if somebody can help me make sense of the results. In my test, I generate a DataArray da time series with a 365_day calendar using cftime. I then write that DataArray in a netCDF file and read it in another DataArray da2

Code Sample, a copy-pastable example if possible

```python import xarray as xr import cftime import numpy as np

generate data for 365_days calendar

units = 'days since 2000-01-01 00:00' time_365 = cftime.num2date(np.arange(0, 10 * 365), units, '365_day') da = xr.DataArray(np.arange(time_365.size), coords = [time_365], dims = 'time', name = 'data')

write dataArray in netcdf and read it in new DataArray

da.to_netcdf('data_365.nc', 'w') da2 = xr.open_dataset('data_365.nc').data

try resample da

try: mean = da.resample(time='Y').mean() print(mean.values) except TypeError: print('got TypeError for da')

try resample da2

mean = da2.resample(time = 'Y').mean() print (mean.values) ```

Problem description

As seen in the code the resampledoes not work for da while it does for da2. The problem is related to the the type of da.time which is cftime.DatetimeNoLeap while da2.time is a datetime64. I thought that xarray is using cftime to make the conversion from time numerical values to dates but it looks to me as if it is not the case.

I wonder if this makes sense or if it is something that should eventually be corrected.

INSTALLED VERSIONS In [6]: print (cftime.version) 1.0.1

------------------ commit: None python: 3.6.5.final.0 python-bits: 64 OS: Darwin OS-release: 17.7.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: fr_CA.UTF-8 LOCALE: fr_CA.UTF-8 xarray: 0.10.8 pandas: 0.23.0 numpy: 1.14.3 scipy: 1.1.0 netCDF4: 1.4.1 h5netcdf: None h5py: 2.7.1 Nio: None zarr: None bottleneck: 1.2.1 cyordereddict: None dask: 0.17.5 distributed: 1.21.8 matplotlib: 2.2.2 cartopy: None seaborn: 0.8.1 setuptools: 39.1.0 pip: 10.0.1 conda: 4.5.11 pytest: 3.5.1 IPython: 6.4.0 sphinx: 1.7.4
 
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