PERF: unstack

[jbrockmendel]

• closes #xxxx
• tests added / passed
• Ensure all linting tests pass, see here for how to run them
• whatsnew entry

Avoids expensive get_indexer calls.

from asv_bench.benchmarks.reshape import *

self = Unstack()
self.setup("category")

%timeit self.time_full_product("category")
58.8 ms ± 1.52 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)  # <- master
31.6 ms ± 1.98 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)  # <- PR

[jreback]

does this allow us to get rid of some cython code (that i wrote a long time ago) to do unstacking?

[jbrockmendel]

does this allow us to get rid of some cython code (that i wrote a long time ago) to do unstacking?

no

[jreback]

is this still called?

[jbrockmendel]

Yes, just fewer times

…

On Wed, Aug 18, 2021 at 8:20 AM Jeff Reback ***@***.***> wrote: ***@***.**** requested changes on this pull request. ------------------------------ In pandas/core/reshape/reshape.py <#43025 (comment)>: > @@ -287,7 +287,7 @@ def get_new_values(self, values, fill_value=None): return new_values, new_mask - def get_new_columns(self, value_columns): + def get_new_columns(self, value_columns: Index | None): is this still called? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#43025 (review)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AB5UM6E6WA7525MXYRE3WV3T5PFVRANCNFSM5CEFXWSQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&utm_campaign=notification-email> .