BUG:Inconsistent when use Series.get

[liudengfeng]

• I have checked that this issue has not already been reported.

• [ + ] I have confirmed this bug exists on the latest version of pandas.

• (optional) I have confirmed this bug exists on the master branch of pandas.

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Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.

Code Sample, a copy-pastable example

# Your code here
import pandas as pd
animals = pd.Series(['lama', 'cow', 'lama', 'beetle', 'lama'],index=[-1,0,1,2,3])
animals.get([1,-1,2]) # ok

animals = pd.Series(['lama', 'cow', 'lama', 'beetle', 'lama'])
animals.get([1,2]) # ok

BUT：
animals.get([1,-1,2]) return None!!!

Problem description

[this should explain why the current behaviour is a problem and why the expected output is a better solution]

Expected Output

If you mix existing labels with non-existent labels, at least need to return the corresponding results of the existing labels?

Output of pd.show_versions()

INSTALLED VERSIONS

commit : 2a7d332
python : 3.8.5.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.18362
machine : AMD64
processor : Intel64 Family 6 Model 142 Stepping 12, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : Chinese (Simplified)_China.936

pandas : 1.1.2
numpy : 1.19.1
pytz : 2020.1
dateutil : 2.8.1
pip : 20.2.2
setuptools : 49.6.0.post20200814
Cython : 0.29.21
pytest : 6.0.1
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.5.2
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 2.11.2
IPython : 7.18.1
pandas_datareader: None
bs4 : 4.9.1
bottleneck : 1.3.2
fsspec : 0.8.0
fastparquet : None
gcsfs : None
matplotlib : 3.3.1
numexpr : 2.7.1
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : 1.0.1
pytables : None
pyxlsb : None
s3fs : None
scipy : 1.5.2
sqlalchemy : 1.3.19
tables : 3.6.1
tabulate : None
xarray : None
xlrd : 1.2.0
xlwt : None
numba : None

[paste the output of pd.show_versions() here leaving a blank line after the details tag]

[phofl]

Hi,

thanks for your report. This stopped working with release 1.0 as described in https://pandas.pydata.org/docs/user_guide/indexing.html#indexing-deprecate-loc-reindex-listlike. This is more or less translated into animals.loc[[1,-1,2]].

But we could maybe clarify the documentation here?

Edit: Actually that did not work before 1.0 either.

[Akashkambale-Creater]

Hi,

Python read the data line by line, in the second animal data-frame that particular (-1) index is not present that's why it's not returning any value.

You can try

Your code here

import pandas as pd
animals = pd.Series(['lama', 'cow', 'lama', 'beetle', 'lama'],index=[-1,0,1,2,3])
print(animals.get([1,-1,2]))

animals = pd.Series(['lama', 'cow', 'lama', 'beetle', 'lama'])
print(animals.get([1,2]))

print(animals.get([1,2]))