[MRG] Better in-out support

[chkoar]

Reference Issue

Follows #673. Fixes #666.

What does this implement/fix? Explain your changes.

Adds better support for pandas and simple lists, if this is the case.
Gradually we could support more array data types.

Any other comments?

I created new type for the job just to keep some state.
The intention is to be private, thus no tested are provided.
Existing tests are passing, at least on my machine. Let's see what the CIs think.

[pep8speaks]

Hello @chkoar! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2020-02-07 14:21:40 UTC

[codecov]

Codecov Report

Merging #681 into master will increase coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #681      +/-   ##
==========================================
+ Coverage   98.59%   98.65%   +0.05%     
==========================================
  Files          82       82              
  Lines        4850     4907      +57     
==========================================
+ Hits         4782     4841      +59     
+ Misses         68       66       -2

Impacted Files	Coverage Δ
imblearn/over_sampling/_smote.py	97.21% <ø> (+0.51%)	⬆️
imblearn/over_sampling/_random_over_sampler.py	100% <ø> (ø)	⬆️
...ling/_prototype_selection/_random_under_sampler.py	100% <ø> (ø)	⬆️
...n/under_sampling/_prototype_selection/_nearmiss.py	98.59% <100%> (ø)	⬆️
imblearn/utils/_validation.py	100% <100%> (ø)	⬆️
imblearn/utils/estimator_checks.py	96.68% <100%> (+0.38%)	⬆️
imblearn/utils/tests/test_validation.py	100% <100%> (ø)	⬆️

---

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[lgtm-com]

This pull request introduces 1 alert when merging 35d7af9 into 3ede269 - view on LGTM.com

new alerts:

• 1 for Variable defined multiple times

[lgtm-com]

This pull request introduces 1 alert when merging 182dc6e into 3ede269 - view on LGTM.com

new alerts:

• 1 for Variable defined multiple times

[chkoar]

@glemaitre I think that there is no need to attach that object to the the sampler instance. So, when you have time check again.

[glemaitre]

This is good

[glemaitre]

Arfff I forgot to check the what's new. Could you make an entry in what's new in 0.6.2
I will make probably a bug fix release because we add quite a lot of feedback on the bug in #666

[chkoar]

@glemaitre see #682 and update it if you want.