MAINT: asv with py3 on windows

[chris-b1]

Since benchmarking on python 3, no longer want to install libpython

[codecov]

Codecov Report

Merging #16139 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #16139   +/-   ##
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  Coverage   90.84%   90.84%           
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  Files         159      159           
  Lines       50779    50779           
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  Hits        46128    46128           
  Misses       4651     4651

Flag	Coverage Δ
#multiple	88.62% <ø> (ø)	⬆️
#single	40.33% <ø> (ø)	⬆️

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[codecov]

Codecov Report

Merging #16139 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #16139   +/-   ##
=======================================
  Coverage   90.84%   90.84%           
=======================================
  Files         159      159           
  Lines       50779    50779           
=======================================
  Hits        46128    46128           
  Misses       4651     4651

Flag	Coverage Δ
#multiple	88.62% <ø> (ø)	⬆️
#single	40.33% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #16139 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #16139   +/-   ##
=======================================
  Coverage   90.84%   90.84%           
=======================================
  Files         159      159           
  Lines       50779    50779           
=======================================
  Hits        46128    46128           
  Misses       4651     4651

Flag	Coverage Δ
#multiple	88.62% <ø> (ø)	⬆️
#single	40.33% <ø> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[jorisvandenbossche]

Can you keep those entries but specify it is only for python 3?
Then for people benchmarking on python 2, it keeps working

[chris-b1]

@jorisvandenbossche - asv actually still works on python 2 with this change, as long as the right version of MSVC is installed (https://www.microsoft.com/en-us/download/details.aspx?id=44266).

This would be the same compiler our release binaries / tests are built with, and easy enough to install now (wasn't always), so I think we should prefer it over the mingw toolchain.

[jorisvandenbossche]

OK, I currently don't use python 2 on windows anymore, so won't push too hard. I just know that being able to just conda install the correct compilers was very handy at that time :-) But if that has improved, then certainly OK!

Our contributing docs still mention libpython: http://pandas-docs.github.io/pandas-docs-travis/contributing.html#creating-a-windows-development-environment

[chris-b1]

Yeah, that's fair, I think MSVC would be the 'recommended' way now, but libpython is still valid for 2.x. I added a comment that hopefully is a decent middle ground?

[jorisvandenbossche]

thanks!