STYLE fix pylint issues

[MarcoGorelli]

In https://github.com/pandas-dev/pandas/pull/48759/files we're introduced pylint, but have turned off its warnings as there's a lot of them:

pandas/pyproject.toml

Lines 36 to 67 in d719840

	disable = [
	"C",
	"R",
	"W",
	"abstract-class-instantiated",
	"access-member-before-definition",
	"bad-super-call",
	"c-extension-no-member",
	"function-redefined",
	"import-error",
	"inherit-non-class",
	"invalid-repr-returned",
	"invalid-unary-operand-type",
	"misplaced-bare-raise",
	"no-member",
	"no-method-argument",
	"no-name-in-module",
	"no-self-argument",
	"no-value-for-parameter",
	"non-iterator-returned",
	"not-an-iterable",
	"not-callable",
	"redundant-keyword-arg",
	"too-many-function-args",
	"undefined-variable",
	"unexpected-keyword-arg",
	"unpacking-non-sequence",
	"unsubscriptable-object",
	"unsupported-assignment-operation",
	"unsupported-membership-test",
	"used-before-assignment",
	]

Task here is:

1. pick one of the above warnings / errors, and remove it from pyproject.toml
2. run pre-commit run pylint --hook-stage manual --all-files. If this already passes, skip to step 4.
3. fixup any warnings that result
4. if pre-commit run pylint --hook-stage manual --all-files passes, then stage and commit your changes and open a pull request

If you believe a warning is a false-positive, then it's OK to ignore it in-line, e.g.

df.rename(id, mapper=id)  # pylint: disable=redundant-keyword-arg

Please comment here which pylint warning you'll work on before starting so we don't duplicate work. No need to ask for permission to work on this, and no need to comment "take" as multiple people can work on this concurrently

---

NOTE: please do not write "closes #48855" in your PR

---

checks we probably can't turn off:

• too-many-function-args
• unsubscriptable-object
• unsupported-assignment-operation
• no-name-in-module
• no-member
• import-error
• not-an-iterable
• invalid-unary-operator-type
• invalid-name
• wrong-import-order (and anything else related with imports)
• unexpected-keyword-argument
• use-implicit-booleaness-not-len
• use-implicit-booleaness-not-comparison
• comparison-with-itself
• no-else-*
• line-too-long
• overridden-final-method
• singleton-comparison
• unsupported-membership-test
• pointless-statement
• broad-except
• undefined-variable

If you're not sure whether a check should fit into the above list, please do ask

[shivamurali]

Hi there! I'll get to work on the "used-before-assignment" warning and remove it from the pyproject.toml file.

EDIT: PR went stale, anyone else is welcome to work on this

[slackline]

I'll work on removing import-error.

[gulyapulya]

Hi! I am also new to the open source, but I want to contribute, I will work on the "no-method-argument".

[kostyafarber]

Hi! I'll work on inherit-non-class.

[soumilbaldota]

Hi, I will take bad-super-call warning, I have added the pull request above.

[FloHofstetter]

Hi, I will take function-redefined warning.

[rokaicker]

Hi ! I'm new to open source, but I'd like to tackle the too-many-function-args!

[MarcoGorelli]

thanks @rokaicker - that one's probably too hard to turn off for now, without going through a deprecation cycle, but there's lot's of others to choose

I've added this one to the description as one that's probably not possible to turn off for now

[jetale]

working on "unsupported-assignment-operation"

[Exoutia]

i am working on "no-self-argument"

[shalearkane]

I am working on "unexpected-keyword-arg"

[roadswitcher]

I am working on no-name-in-module

[Leviob]

Hi, I would like to work on "used-before-assignment," but I'm aware it was already claimed by @shivamurali. Can I submit my own PR for it? Thanks.

[joaomarcoscrs]

I'll work on the not-callable

[rAwsam]

Hi! I am also new to the open source, but I want to contribute, I will work on the "undefined-variable"

[TejasCreative]

I'll work on no-member!

[MarcoGorelli]

sorry, --hook-stage

[angularOcean]

Thanks --hook-stage fixed the issue. Also, after running a check on unused-argument, there turned up several hundred lines with the issue and from a quick look of a sampling of them, a large proportion of them are false positives i.e. 'col' in:
def time_iteritems_indexing(self): for col in self.df3: self.df3[col]
I can mark this as a false positive but there would be a lot of them. Would it be better to continue keeping this warning turned off?

[MarcoGorelli]

we can probably keep it off

We're probably scraping the barrel here with this issue, I think we've probably enabled most of the most meaningful ones

There's still some files to do in #49656 if you fancy that though

[seanjedi]

Is anyone working on unsupported-membership-test?
Can I take that task?

[angularOcean]

I took a look and I think use-implicit-booleaness-not-comparison is worth working on too

[angularOcean]

I will also work on use-implicit-booleaness-not-len and see if that can enabled as well

[natmokval]

Hi @MarcoGorelli , I checked pylint warning singleton-comparison and suggest keeping it off. Only false-positive warnings are raised on 8 lines (in 4 files); on every line, flake8 warnings, such as noqa: E711 or noqa: E712, are ignored.

For example:
https://github.com/pandas-dev/pandas/blob/main/pandas/tests/series/test_arithmetic.py#L827

https://github.com/pandas-dev/pandas/blob/main/pandas/tests/frame/indexing/test_where.py#L828

[seanjedi]

Hi @MarcoGorelli
I've started to work on unsupported-membership-test if that is alright.
I started working on it here: #49848
I have not opened up the PR for review yet since there are still some issues I am trying to debug, once I have them resolved then I will open up the PR.

[MarcoGorelli]

thanks @seanjedi - let's keep that one off too, I think they're all false positives and we risk annoying contributors

pointless-string-statement might be a good one - strings are sometimes used as comments, and it's probably worth converting them to comments because this check found an issue when I tried it

[CerqueiraMatheus]

I will work on access-member-before-definition

[seanjedi]

@MarcoGorelli Alright, thanks for letting me know!
I will work on pointless-string-statement then.
I will create a new branch, and if anyone wants to check what I have done for unsupported-membership-test then they can checkout my branch.
I agree though, that a lot of the changes were not really necessary, and would complicate some of the code.

[seanjedi]

@MarcoGorelli I have worked on implementing the changes for pointless-string-statement here: #49880

[roadswitcher]

Found just over 30 instances of broad-except which appeared to be false positives -- do we want to keep this warning disabled?? (ref PR #49910 for example)

[uzzell]

I'll take unnecessary-list-index-lookup.

[MarcoGorelli]

Found just over 30 instances of broad-except which appeared to be false positives -- do we want to keep this warning disabled?? (ref PR #49910 for example)

yeah let's do that

[roadswitcher]

Found just over 30 instances of broad-except which appeared to be false positives -- do we want to keep this warning disabled?? (ref PR #49910 for example)

yeah let's do that

PR closed.

[bang128]

Has anyone taken line-too-long yet? Can I work on it?

[MarcoGorelli]

Thanks everyone for your contributions!

I think we've probably taken the most valuable ones already, so I think we can stop asking for contributions on this one.

If anyone comes across a pylint code which can be removed and which adds then value, then please do submit a PR to fix it! You're still welcome to do that, I just think it's time to close the issue

Thanks all 🙏