BUG: extra leading space in to_string when index=False

[onshek]

• closes Bug on .to_string(index=False) #24980
• tests added / passed
• passes black pandas
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

This PR is mainly from #29670 contributed by @charlesdong1991, and I made a few changes on his work.
The code have passed all tests modified and added in test_format.py and test_to_latex.py.
Any comment is welcomed!

[pep8speaks]

Hello @onshek! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

There are currently no PEP 8 issues detected in this Pull Request. Cheers! 🍻

Comment last updated at 2020-09-06 02:50:26 UTC

[charlesdong1991]

@onshek nice! this probably needs to be moved to 1.2 whatsnew note?

[onshek]

@onshek nice! this probably needs to be moved to 1.2 whatsnew note?

done

[jreback]

lgtm. ping on green.

@charlesdong1991 if any comments.

[charlesdong1991]

@onshek since the default has changed from None to True, maybe nicer to update the docstring a bit as well, something like?

# current doc
leading_space : bool, optional

# suggested?
leading_space : bool, optional, default is True

[onshek]

@onshek since the default has changed from None to True, maybe nicer to update the docstring a bit as well, something like?

# current doc
leading_space : bool, optional

# suggested?
leading_space : bool, optional, default is True

Sure, working on it.

[onshek]

@jreback @charlesdong1991 Done. Thanks for your reviews :)

[jreback]

small comment, ping on green.

[jreback]

can you also that this would affect DataFrame.to_latex and DataFrame.to_string

[onshek]

can you also that this would affect DataFrame.to_latex and DataFrame.to_string

"also" waht? Do you mean give a mark here like:

Bug in :meth:Series.to_string adding a leading space when index=False and this would affect DataFrame.to_latex and DataFrame.to_string (:issue:24980)

[charlesdong1991]

Suggested change

	- Bug in :meth:`Series.to_string` adding a leading space when ``index=False`` (:issue:`24980`)
	- Bug in :meth:`Series.to_string`, :meth:`DataFrame.to_string`, and :meth:`DataFrame.to_latex` adding a leading space when ``index=False`` (:issue:`24980`)

ping if you could make this change.

[onshek]

updated :)

[jreback]

thanks @onshek very nice!