issues: 1323521079

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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
1323521079 I_kwDOAMm_X85O41Q3 6852 Testing DataArray equality using built-in '==' operator leads to mutilated DataArray.attrs dictionary 17813788 closed 0     3 2022-07-31T17:04:43Z 2022-08-31T07:16:15Z 2022-08-31T07:16:15Z NONE      

What happened?

In previous versions of xarray, testing numerical equivalence of two DataArrays was possible using the built-in operator '==' and without side affects. Now in version 2022.6.0, when one DataArray lacks an attribute that the other DataArray has, the DataArray with the attribute is mutilated during comparison leading to an empty attrs dictionary.

What did you expect to happen?

DataArray_1 == DataArray_2 should not have side affects.

Minimal Complete Verifiable Example

Python import xarray as xr da_withunits = xr.DataArray([1, 1, 1], coords={"frequency": [1, 2, 3]}) da_withunits.frequency.attrs["units"] = "GHz" print(da_withunits.frequency.units) da_withoutunits = xr.DataArray([1, 1, 1], coords={"frequency": [1, 2, 3]}) print(da_withunits == da_withoutunits) print(da_withunits.frequency.units)

MVCE confirmation

  • [X] Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
  • [X] Complete example — the example is self-contained, including all data and the text of any traceback.
  • [X] Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
  • [X] New issue — a search of GitHub Issues suggests this is not a duplicate.

Relevant log output

Python GHz <xarray.DataArray (frequency: 3)> array([ True, True, True]) Coordinates: * frequency (frequency) int32 1 2 3 Traceback (most recent call last): File "d:\projects\ssdv\mvce.py", line 9, in <module> print(da_withunits.frequency.units) File "...\AppData\Local\Programs\Python\Python39\lib\site-packages\xarray\core\common.py", line 256, in __getattr__ raise AttributeError( AttributeError: 'DataArray' object has no attribute 'units'

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS ------------------ commit: None python: 3.9.13 (tags/v3.9.13:6de2ca5, May 17 2022, 16:36:42) [MSC v.1929 64 bit (AMD64)] python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: Intel64 Family 6 Model 85 Stepping 4, GenuineIntel byteorder: little LC_ALL: None LANG: None LOCALE: ('English_United States', '1252') libhdf5: None libnetcdf: None xarray: 2022.6.0 pandas: 1.4.3 numpy: 1.23.1 scipy: 1.9.0 netCDF4: None pydap: None h5netcdf: None h5py: None Nio: None zarr: None cftime: None nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: None distributed: None matplotlib: 3.5.2 cartopy: None seaborn: None numbagg: None fsspec: None cupy: None pint: None sparse: None flox: None numpy_groupies: None setuptools: 63.2.0 pip: 22.2.1 conda: None pytest: 7.1.2 IPython: 8.4.0 sphinx: None 
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   completed 13221727 issue

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