PERF: performance improvement in MultiIndex.sortlevel

[behzadnouri]

-------------------------------------------------------------------------------
Test name                                    | head[ms] | base[ms] |  ratio   |
-------------------------------------------------------------------------------
multiindex_sortlevel_int64                   | 664.1977 | 2443.2590 |   0.2718 |
-------------------------------------------------------------------------------
Test name                                    | head[ms] | base[ms] |  ratio   |
-------------------------------------------------------------------------------

Ratio < 1.0 means the target commit is faster then the baseline.
Seed used: 1234

Target [dd31bae] : performance improvement in MultiIndex.sortlevel
Base   [c4a996a] : Merge pull request #9411 from dashesy/add_sql_test

test sql table name

[shoyer]

Both idx.size and ids.max() are integers, yes?

I find using and for integers rather confusing. Perhaps this could be: (idx.max() if ids.size else 0) + 1

[behzadnouri]

boolean-operations:

The expression x and y first evaluates x; if x is false, its value is returned; otherwise, y is evaluated and the resulting value is returned.

note that the documentation follows with an example of s or 'foo', i.e. oring two strings, as a use-case of boolean operations.

[jreback]

@behzadnouri I agree with @shoyer here. We get the idiom, but I don't think a casual glance is intuitve here. Pls change to what @shoyer suggests.

[behzadnouri]

i gave an example from python's documentation that this is an actual use-case for boolean operations:

This is sometimes useful, e.g., if s is a string that should be replaced by a default value if it is empty, the expression s or 'foo' yields the desired value.

this is right off from python's documentation, and i have seen it used a lot.

that said, if you like to change it, please do.

[jreback]

I get that it is from python docs
but not all of that idioms are useful
in the context of assignment with a value that could be None I would agree with you
but these are integers and it's not obvious at all

pls make the change

[jreback]

looks good otherwise, ping when green after that change.

[jreback]

@behzadnouri thanks!