Make parameter keep=False keep duplicates for nlargest/nsmallest

Code Sample, a copy-pastable example if possible

>>> s = pd.Series([10,9,8,7,7,7,6])
>>> s.nlargest(4)
0    10
1     9
2     8
3     7
dtype: int64

Problem description

The docstrings list False as one of the possible argument values for keep. pandas raises a ValueError when attempting to use this parameter.

Expected Output

It would be nice to have nlargest work like this.

>>> s.nlargest(4, keep=False)
0    10
1     9
2     8
3     7
4     7
5     7

Output of pd.show_versions()

# Paste the output here pd.show_versions() here INSTALLED VERSIONS ------------------ commit: None python: 3.6.1.final.0 python-bits: 64 OS: Darwin OS-release: 15.6.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8

pandas: 0.20.2 pytest: 3.0.7 pip: 9.0.1 setuptools: 35.0.2 Cython: 0.25.2 numpy: 1.13.0 scipy: 0.19.0 xarray: None IPython: 6.0.0 sphinx: 1.5.5 patsy: 0.4.1 dateutil: 2.6.0 pytz: 2017.2 blosc: None bottleneck: 1.2.0 tables: 3.4.2 numexpr: 2.6.2 feather: None matplotlib: 2.0.2 openpyxl: 2.4.7 xlrd: 1.0.0 xlwt: 1.2.0 xlsxwriter: 0.9.6 lxml: 3.7.3 bs4: 4.6.0 html5lib: 0.999999999 sqlalchemy: 1.1.9 pymysql: None psycopg2: None jinja2: 2.9.6 s3fs: None pandas_gbq: None pandas_datareader: 0.3.0.post

[tdpetrou]

@gfyoung This doesn’t make sense to me. The keep option is only important whenever there are ties for the last value. Arguably, the most useful thing to do is to keep all of the ties which would be keep=False. This option still exists in the docstrings in 0.21.

Also, the duplicated method has same three options so it matches that. Additionally, it was just recently removed without discussion.

edit: A better value for the parameter would be keep='all'

[artinthetrees]

it would be useful also to have a keep option of “none”!

s = pd.Series([10,9,8,7,7,7,6]) s.nlargest(4) 0 10 1 9 2 8 dtype: int64