Fixing melt() when col_level>0 in a multi-index column

[rbavishi]

Example Input DataFrame -

import pandas as pd x = pd.DataFrame([[0, 1], [2, 3]], columns=[list('AB'), list('CD')]) """ A B C D 0 0 1 1 2 3 """ x.melt(col_level=1, id_vars=['C'], value_vars=['D']) 

Current Output -

KeyError: 'C' 

Desired Output -

 C variable value 0 0 D 1 1 2 D 3 

[pep8speaks]

Hello @rbavishi! Thanks for updating the PR.

Cheers ! There are no PEP8 issues in this Pull Request. 🍻

Comment last updated on April 10, 2018 at 05:37 Hours UTC

[codecov]

Codecov Report

Merging #20646 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@ Coverage Diff @@ ## master #20646 +/- ## ========================================== + Coverage 91.83% 91.84% +<.01%  ========================================== Files 153 153 Lines 49269 49271 +2 ========================================== + Hits 45247 45251 +4  + Misses 4022 4020 -2

Flag	Coverage Δ
#multiple	90.22% <100%> (ø)	⬆️
#single	41.9% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/core/reshape/melt.py	97.39% <100%> (+0.04%)	⬆️
pandas/util/testing.py	84.59% <0%> (+0.2%)	⬆️

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[gfyoung]

@rbavishi : Thanks for submitting this! A couple of things:

1. Before submitting a PR, you should generally submit an issue. The content of your PR message would have been perfect for that!

2. You'll need to add tests and an entry into our whatsnew file for 0.23.0

[jreback]

yeah this is probably broken. need some tests

[jreback]

closing as stale