CLN: Refactor some sorting code in Index set operations

[reidy-p]

• Related to ENH: Add sort parameter to set operations for some Indexes and adjust… #24521
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff

This is a pre-cursor to #24521 and cleans up some of the sorting code in set operations on Index.

[reidy-p]

There are a couple of places where the above warning was given. But now that the safe_sort function is used the warning is no longer given because safe_sort tries to sort some "unorderable" types:

pandas/pandas/core/sorting.py

Lines 448 to 466 in 091cfbb

	def sort_mixed(values):
	# order ints before strings, safe in py3
	str_pos = np.array([isinstance(x, string_types) for x in values],
	dtype=bool)
	nums = np.sort(values[~str_pos])
	strs = np.sort(values[str_pos])
	return np.concatenate([nums, np.asarray(strs, dtype=object)])
	sorter = None
	if PY3 and lib.infer_dtype(values) == 'mixed-integer':
	# unorderable in py3 if mixed str/int
	ordered = sort_mixed(values)
	else:
	try:
	sorter = values.argsort()
	ordered = values.take(sorter)
	except TypeError:
	# try this anyway
	ordered = sort_mixed(values)

[jreback]

yep, this is the intent of the function

[codecov]

Codecov Report

Merging #24533 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24533   +/-   ##
=======================================
  Coverage   31.88%   31.88%           
=======================================
  Files         166      166           
  Lines       52427    52427           
=======================================
  Hits        16714    16714           
  Misses      35713    35713

Flag	Coverage Δ
#multiple	30.28% <0%> (ø)	⬆️
#single	31.88% <0%> (ø)	⬆️

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[codecov]

Codecov Report

Merging #24533 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #24533   +/-   ##
=======================================
  Coverage   31.88%   31.88%           
=======================================
  Files         166      166           
  Lines       52427    52427           
=======================================
  Hits        16714    16714           
  Misses      35713    35713

Flag	Coverage Δ
#multiple	30.28% <0%> (ø)	⬆️
#single	31.88% <0%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 091cfbb...f8bfb91. Read the comment docs.

[jreback]

thanks @reidy-p