Implement missing DataFrame/Series/Index APIs

[HyukjinKwon]

I am opening this as a reminder. Probably I might keep opening and closing for each release - not sure yet about it. I don't intend to open this so long time.

To get to the point, eventually we should fix all of the missing APIs here:
https://github.com/databricks/koalas/blob/master/databricks/koalas/missing/series.py
https://github.com/databricks/koalas/blob/master/databricks/koalas/missing/frame.py
https://github.com/databricks/koalas/blob/master/databricks/koalas/missing/indexes.py
https://github.com/databricks/koalas/blob/master/databricks/koalas/missing/groupby.py

Please open a separate issue to start to work on implementing them.

[abishekganesh72]

@HyukjinKwon any particular functions that need to be done first?

[HyukjinKwon]

I don't have in my mind yet. We should implement all of them (unless it violates our design principles) and I wanted to pin the reminder for now :).

[HyukjinKwon]

hey @garawalid, let's file a separate issue next time just for separate trackability

[garawalid]

@HyukjinKwon Okay. I'll open one that contains missing methods for 10-minute tutorial with Koalas (#196)

[shril]

@HyukjinKwon, @garawalid, @abishekganesh72, for the sake of convenience, let's pick up 10 functions for now and in the meantime, we can add more to this list.
This will ultimately help us with better communication between contributors.

I am selecting 10 frequently used unsupported functions for frame.py -

• add
• aggregate
• dot
• eq
• first
• keys
• last
• info
• items
• le

[shril]

I am starting with DataFrame.first(), DataFrame.last() and DataFrame.keys().

[HyukjinKwon]

sounds good :-). Actually, can you get rid of add in the list? I plan to do them all like #401

I plan to add those:

• add
• radd
• div
• divide
• rdiv
• truediv
• rtruediv
• mul
• multiply
• rmul
• sub
• substract
• rsub

soon at frame.py in one go.

If somebody takes this one, then it's even better to me :-).

[shril]

@HyukjinKwon, I already have 2 PRs on my plate.
I will take it once I complete my set of functions.

[HyukjinKwon]

I opened a PR for mine, #427

[manuzhang]

@shril Any progress on your remaining functions ?

[HyukjinKwon]

@manuzhang feel free to take over if we don't get response within few days.

[xinrong-meng]

Hi @HyukjinKwon, since we have #1929 for tracking missing API, shall we close this issue? Thank you!

[itholic]

Hi @HyukjinKwon, since we have #1929 for tracking missing API, shall we close this issue? Thank!

+1