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xr.Dataset.map drops attrs of DataArray

See original GitHub issue

MCVE Code Sample

import xarray as xr
import numpy as np

ds = xr.DataArray([1, 2], attrs=dict(tst="DataArray")).to_dataset(name="data")
ds.attrs["tst"] = "Dataset"
ds.map(np.mean, keep_attrs=True).data

returns

<xarray.DataArray 'data' ()>
array(1.5)

Expected Output

<xarray.DataArray 'data' ()>
array(1.5)
Attributes:
    tst:      DataArray

Problem Description

Applying xr.Dataset.map(..., keep_attrs=True) does not retain the attributes of the DataArrays. Should it?

In constrast ds.mean(keep_attrs=True) retains DataArray-level attrs.

EDIT: corrected example

Output of `xr.show_versions()`

INSTALLED VERSIONS

commit: bd4f048bdb5a5a356a5603904d96a676037d1b6e python: 3.7.3 | packaged by conda-forge | (default, Jul 1 2019, 21:52:21) [GCC 7.3.0] python-bits: 64 OS: Linux OS-release: 4.12.14-lp151.28.32-default machine: x86_64 processor: x86_64 byteorder: little LC_ALL: None LANG: en_GB.UTF-8 LOCALE: en_US.UTF-8 libhdf5: 1.10.5 libnetcdf: 4.6.2

xarray: 0.14.0+117.gbd4f048b.dirty pandas: 0.25.2 numpy: 1.17.3 scipy: 1.3.1 netCDF4: 1.5.1.2 pydap: installed h5netcdf: 0.7.4 h5py: 2.10.0 Nio: 1.5.5 zarr: 2.3.2 cftime: 1.0.4.2 nc_time_axis: 1.2.0 PseudoNetCDF: installed rasterio: 1.1.0 cfgrib: 0.9.7.2 iris: 2.2.0 bottleneck: 1.2.1 dask: 2.6.0 distributed: 2.6.0 matplotlib: 3.1.1 cartopy: 0.17.0 seaborn: 0.9.0 numbagg: installed setuptools: 41.6.0.post20191029 pip: 19.3.1 conda: None pytest: 5.2.2 IPython: 7.9.0 sphinx: None

Issue Analytics

State:
Created 4 years ago
Comments:6 (3 by maintainers)

Top GitHub Comments

1reaction

max-sixtycommented, Dec 6, 2019

(forgive me, am on vacation)

I actually didn’t know about the multiple levels of attrs. Given that does exist, I agree with @dcherian re keep_attrs impacting individual variable attrs too.

While it is a behavior change, I think it’s fine: the current behavior is somewhere between a bug and an undocumented artefact. Unless others see a more material change here?

0reactions

TomNicholascommented, Dec 13, 2019

When I wrote the (set_options) keep_attrs switch in then I intended it to function as a global switch, so ensuring that individual DataArray attrs are also propagated fits with that intention. I just apparently never thought of this case.

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