issues: 849751721

This data as json

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
849751721 MDU6SXNzdWU4NDk3NTE3MjE= 5106 to_zarr() fails on time coordinate in append mode 40218891 closed 0     4 2021-04-03T22:26:11Z 2021-04-20T12:04:06Z 2021-04-20T04:41:07Z NONE      

What happened: When the append dimension coordinates are times and the dimension of the first dataset written is 1, consecutive appends forget the hour part of the coordinate. What you expected to happen: The time coordinate should be set correctly.

Minimal Complete Verifiable Example:

``` import pandas as pd import xarray as xr reftime = [pd.Timestamp(2021, 2, 21, 0)] x = [0] dims = ('reftime', 'x') d = np.array([['A']]) ds1 = xr.Dataset(data_vars={'v': (dims, d)}, coords={'reftime': reftime, 'x': x}) _ = ds1.to_zarr('foo', mode='w') reftime = [pd.Timestamp(2021, 2, 21, 6)] d = np.array([['C']]) ds2 = xr.Dataset(data_vars={'v': (dims, d)}, coords={'reftime': reftime, 'x': x}) _ = ds2.to_zarr('foo', append_dim='reftime') ds = xr.open_dataset('foo', engine='zarr') ds.coords['reftime'].values

array(['2021-02-21T00:00:00.000000000', '2021-02-21T00:00:00.000000000'], # should be 2021-02-21T06:00:00.000000000 dtype='datetime64[ns]') ```

Anything else we need to know?: When the reftime coordinate in the first dataset has dimension 2, the output is correct: ``` import pandas as pd import xarray as xr reftime = [pd.Timestamp(2021, 2, 21, 0), pd.Timestamp(2021, 2, 21, 3)] x = [0] dims = ('reftime', 'x') d = np.array([['A'], ['B']]) ds1 = xr.Dataset(data_vars={'v': (dims, d)}, coords={'reftime': reftime, 'x': x}) _ = ds1.to_zarr('foo', mode='w') reftime = [pd.Timestamp(2021, 2, 21, 6)] d = np.array([['C']]) ds2 = xr.Dataset(data_vars={'v': (dims, d)}, coords={'reftime': reftime, 'x': x}) _ = ds2.to_zarr('foo', append_dim='reftime') ds = xr.open_dataset('foo', engine='zarr') ds.coords['reftime'].values

array(['2021-02-21T00:00:00.000000000', '2021-02-21T03:00:00.000000000', '2021-02-21T06:00:00.000000000'], dtype='datetime64[ns]') Increment of a full day works fine: import pandas as pd import xarray as xr reftime = [pd.Timestamp(2021, 2, 21, 0)] x = [0] dims = ('reftime', 'x') d = np.array([['A']]) ds1 = xr.Dataset(data_vars={'v': (dims, d)}, coords={'reftime': reftime, 'x': x}) _ = ds1.to_zarr('foo', mode='w') reftime = [pd.Timestamp(2021, 2, 22, 0)] d = np.array([['C']]) ds2 = xr.Dataset(data_vars={'v': (dims, d)}, coords={'reftime': reftime, 'x': x}) _ = ds2.to_zarr('foo', append_dim='reftime') ds = xr.open_dataset('foo', engine='zarr') ds.coords['reftime'].values

array(['2021-02-21T00:00:00.000000000', '2021-02-22T00:00:00.000000000'], dtype='datetime64[ns]') ``` Environment:

Output of <tt>xr.show_versions()</tt> INSTALLED VERSIONS ------------------ commit: None python: 3.8.8 | packaged by conda-forge | (default, Feb 20 2021, 16:22:27) [GCC 9.3.0] python-bits: 64 OS: Linux OS-release: 5.10.11-200.fc33.x86_64 machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_CA.UTF-8 LOCALE: en_CA.UTF-8 libhdf5: 1.10.6 libnetcdf: 4.7.4 xarray: 0.17.0 pandas: 1.2.3 numpy: 1.20.2 scipy: 1.6.2 netCDF4: 1.5.6 pydap: None h5netcdf: 0.10.0 h5py: 3.1.0 Nio: None zarr: 2.7.0 cftime: 1.4.1 nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: 0.9.8.5 iris: None bottleneck: 1.3.2 dask: 2021.04.0 distributed: 2021.04.0 matplotlib: 3.4.1 cartopy: None seaborn: None numbagg: None pint: None setuptools: 49.6.0.post20210108 pip: 21.0.1 conda: None pytest: None IPython: 7.22.0 sphinx: None 
{
    "url": "https://api.github.com/repos/pydata/xarray/issues/5106/reactions",
    "total_count": 0,
    "+1": 0,
    "-1": 0,
    "laugh": 0,
    "hooray": 0,
    "confused": 0,
    "heart": 0,
    "rocket": 0,
    "eyes": 0
}
   completed 13221727 issue

Links from other tables