Write "Working with InferenceData" page

[OriolAbril]

Tell us about it

As part of the documentation revamp described in #1331. We should add a page explaining how to work with InferenceData and show several common tasks. The guide should cover at least the following topics:

#1506

• Stacking dimensions (maybe even reshaping? reshaping is a bit crazy though), fancy chain/draw extraction methods from Add helper function to easily stack chain and draws dimensions #1469
• Some grouping/aggregating of data: mean
• Get values and coordinates as arrays
• Slice inferenceData objects

Pending

• modifying, transforming and/or creating a variable within an InferenceData group or groups. See add example about transforming and/or creating variables #641 for code examples that can be used for this
• how to combine/merge/extend multiple InferenceData objects
• Coordinate modification. Maybe something like Posterior predictive check (plot_ppc) with dataframe encoding.  #1461 (includes example code and explanation)
• ...

Thoughts on implementation

Feel free to tackle parts of the issue instead of generating the whole section at once.

It is also probably a good idea to add a See also section at the bottom linking to other docs (i.e. pymc3 or pystan docs), blogs and other resources that use inferencedata. For example: https://docs.pymc.io/notebooks/multilevel_modeling.html

[kenkirito]

can i work on this issue

[OriolAbril]

Great, thanks!

[kenkirito]

is there any discord server or any community chat or meetings to attain. I am done with the setup. just wanted to know more about the project

[OriolAbril]

We have a gitter chat available: https://gitter.im/arviz-devs/community, and there are also questions and discussions about the project at PyMC discourse: https://discourse.pymc.io/ and to a lesser extent at Stan discourse: https://discourse.mc-stan.org/

[mjhajharia]

• how to combine/merge/extend multiple InferenceData objects

This sounds good, I recently went through InferenceData docs and they do seem ambiguous and all over the place, the entire issue seems like something that would probably be done over multiple PRs, but I guess to begin with I can take care of this part, I'd like to take it up if noone is working on it at the moment.

[OriolAbril]

Great, note that you have to extend the currently existing notebook at https://github.com/arviz-devs/arviz/blob/main/doc/source/getting_started/WorkingWithInferenceData.ipynb

There are some examples on how to combine inferencedata objects at https://arviz-devs.github.io/arviz/api/generated/arviz.concat.html#arviz.concat.

Using the documentation system outlined in https://documentation.divio.com/, this working with inferencedata page should be a tutorial page (or a bundle of mini tutorials if you prefer), the explanation is in https://github.com/arviz-devs/arviz/blob/main/doc/source/getting_started/XarrayforArviZ.ipynb, and the reference is https://arviz-devs.github.io/arviz/api/inference_data.html. The reference pages may be the easier ones to find right now, so we should probably add some links from reference pages to the working with inferencedata notebook and viceversa, we can add links from the notebook to the reference page of the functions used.