PERF: Use Categorical.equals in CategoricalIndex.equals

[TomAugspurger]

Avoids a materialization of the full array.

import pandas as pd
import numpy as np
import string


a = pd.CategoricalIndex(np.random.choice(list(string.ascii_letters[:10]), 100_000))
b = a.copy()
c = pd.CategoricalIndex(np.random.choice(list(string.ascii_letters[:10]), 100_000))

print("eq-index")
%timeit a.equals(b)

print("ne-index")
%timeit a.equals(c)

timings

case	master	pr
eq-index	3.35 ms	420 µs
ne-index	1.29 ms	451 µs

[pep8speaks]

Hello @TomAugspurger! Thanks for submitting the PR.

• There are no PEP8 issues in the file pandas/core/indexes/category.py !

[codecov]

Codecov Report

Merging #24023 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #24023      +/-   ##
==========================================
+ Coverage   92.31%   92.31%   +<.01%     
==========================================
  Files         161      161              
  Lines       51549    51551       +2     
==========================================
+ Hits        47586    47588       +2     
  Misses       3963     3963

Flag	Coverage Δ
#multiple	90.71% <100%> (ø)	⬆️
#single	42.45% <100%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/indexes/category.py	97.88% <100%> (+0.01%)	⬆️

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[jreback]

thanks!