Add groupby to dataframe

[V1NAY8]

PR on #172

@sethmlarson Can you please review these when free? Still lot of work has to be done. 😕
I implemented groupby to dataframe using composite aggreagation

• Only implemented single aggs and aggregation

• TODO Count, grouped (ed_flights.groupby("Cancelled")), dropna

• One more suggestion needed
  For the following query eland is taking 7.93 seconds, whereas pandas takes 1.56 seconds 😨
  

If you can review the composite aggregation logic, and give some inputs on dropna, grouped, count (how to query ES using filters?). I will proceed on the logic in eland. That's where I was getting stopped.

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[sethmlarson]

Here are some early comments, I need to pull this PR locally and give it a spin to see what the requests and responses look like :)

[V1NAY8]

@sethmlarson
Just a quick one,
If you comment out the following in operations.py at line 701

if b.is_timestamp:
    agg_value = elasticsearch_date_to_pandas_date(
        agg_value, b.es_date_format
    )

There will be an improvement of at least 2 seconds 😲
Then output for the above mentioned query would be:

I guess we have to do something in this:
https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-date-format.html

Any suggestion?

[sethmlarson]

Some more comments for you!

The timestamp field should be the same as what it'd be if it wasn't in the index so if it's a datetime it should still be a datetime. This will be necessary when we go to implement resample().

[V1NAY8]

• Added tests, Could you please check the performance of groupby with different examples?
• I tried some examples, It looks good.
• Ill optimize if required.
• Please add hacktoberfest-accepted to this.

[sethmlarson]

Pulling this locally to take a closer look again! :) Left you a collection of comments. Also a general comment, would be good to start working on more test cases, especially to cover errors.

I need to add pytest-cov so we can see how much test coverage we have :)

[sethmlarson]

jenkins test this please

[V1NAY8]

• Code Coverage Bot will be good :)
• I think we also need to add a Pull request template that has checks in the Contributing.md doc,
• Issue template when raised for issues.

[V1NAY8]

• Made groupby strictly typed
• added more tests (I hope this should cover implemented functionality)

[sethmlarson]

jenkins test this please

[V1NAY8]

Yay! Builds successful 😎

[sethmlarson]

This looks good to me! Will do some tweaking and documenting now that the core functionality is there. Thanks for working so hard on this :)