get_attrs(): helper function to return keys in the sdata.attrs slot in an specific format

[timtreis]

Gets a specific key from sdata.attrs and then returns it either

a) as is (return_as=None) or
b) converted (return_as="dict" | "json" | "df") and potentially flattened (flatten=True, separated by sep)

Needed for spatialdata-db project, but tried to keep it general.

import spatialdata
from spatialdata.datasets import blobs

sdata = blobs()

sdata.attrs  # empty dictionnary
sdata.attrs["test"] = {"a": {"b": 12}, "c": 8}

sdata.write("blobs.zarr", overwrite=True) 
sdata = spatialdata.read_zarr("blobs.zarr") 

sdata.get_attrs(key="test", return_as=None, flatten=False)

{'a': {'b': 12}, 'c': 8}

import spatialdata
from spatialdata.datasets import blobs

sdata = blobs()

sdata.attrs  # empty dictionnary
sdata.attrs["test"] = {"a": {"b": 12}, "c": 8}

sdata.write("blobs.zarr", overwrite=True) 
sdata = spatialdata.read_zarr("blobs.zarr") 

sdata.get_attrs(key="test", return_as="df", flatten=False)

import spatialdata
from spatialdata.datasets import blobs

sdata = blobs()

sdata.attrs  # empty dictionnary
sdata.attrs["test"] = {"a": {"b": 12}, "c": 8}

sdata.write("blobs.zarr", overwrite=True) 
sdata = spatialdata.read_zarr("blobs.zarr") 

sdata.get_attrs(key="test", return_as="df", flatten=True)

import spatialdata
from spatialdata.datasets import blobs

sdata = blobs()

sdata.attrs  # empty dictionnary
sdata.attrs["test"] = {"a": {"b": 12}, "c": 8}

sdata.write("blobs.zarr", overwrite=True) 
sdata = spatialdata.read_zarr("blobs.zarr") 

sdata.get_attrs(key="test", return_as="json", flatten=True)

FYI @Zethson

[codecov]

Codecov Report

Attention: Patch coverage is 86.11111% with 5 lines in your changes missing coverage. Please review.

Project coverage is 91.72%. Comparing base (526a0a2) to head (537617d).
Report is 40 commits behind head on main.

Files with missing lines	Patch %	Lines
src/spatialdata/_core/spatialdata.py	86.11%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #806      +/-   ##
==========================================
- Coverage   91.75%   91.72%   -0.03%     
==========================================
  Files          46       46              
  Lines        7130     7166      +36     
==========================================
+ Hits         6542     6573      +31     
- Misses        588      593       +5     

Files with missing lines	Coverage Δ
src/spatialdata/_core/spatialdata.py	90.60% <86.11%> (-0.18%)	⬇️

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[LucaMarconato]

Convenient and useful API! Great addition 😊