[3/N] Data sources - docs

[ethanwharris]

What does this PR do?

Fixes # (issue)

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure your PR does only one thing, instead of bundling different changes together?
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests? [not needed for typos/docs]
• Did you verify new and existing tests pass locally with your changes?
• If you made a notable change (that affects users), did you update the CHANGELOG?

PR review

• Is this pull request ready for review? (if not, please submit in draft mode)

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

[codecov]

Codecov Report

Merging #272 (28c34c0) into master (e24aa62) will decrease coverage by 0.04%.
The diff coverage is 92.85%.

@@            Coverage Diff             @@
##           master     #272      +/-   ##
==========================================
- Coverage   88.15%   88.11%   -0.05%     
==========================================
  Files          74       74              
  Lines        3564     3567       +3     
==========================================
+ Hits         3142     3143       +1     
- Misses        422      424       +2     

Flag	Coverage Δ
unittests	88.11% <92.85%> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
flash/data/callback.py	100.00% <ø> (ø)
flash/data/data_module.py	92.27% <ø> (ø)
flash/data/transforms.py	100.00% <ø> (ø)
flash/vision/classification/data.py	93.81% <ø> (-0.07%)	⬇️
flash/vision/segmentation/data.py	88.80% <ø> (ø)
flash/tabular/classification/data/data.py	90.83% <71.42%> (-1.35%)	⬇️
flash/data/auto_dataset.py	95.83% <100.00%> (ø)
flash/data/data_source.py	96.72% <100.00%> (ø)
flash/data/process.py	93.59% <100.00%> (-0.04%)	⬇️
flash/vision/detection/data.py	97.26% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e24aa62...28c34c0. Read the comment docs.

[tchaton]

LGTM overall !

[edgarriba]

LGTM

[edgarriba]

is there any way that in the user api we can use directly with strings to make it more clean and avoid to import the data keys class ? to look something like:

 (batch['input'], batch['target']),

[ethanwharris]

This isn't really the user API though. This doc is for best practices to create a new Task, and that would be using the DefaultDataKeys enum. Users of the tasks don't need to use the enum, but when creating new tasks they should be used.

[review-notebook-app]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB