BUG/API: Indexes on empty frames/series should be RangeIndex, are Index[object] #49572
Closed
3 tasks done
Labels
Bug
Constructors
Series/DataFrame/Index/pd.array Constructors
DataFrame
DataFrame data structure
Index
Related to the Index class or subclasses
Needs Triage
Issue that has not been reviewed by a pandas team member
Series
Series data structure
Milestone
Pandas version checks
I have checked that this issue has not already been reported.
I have confirmed this bug exists on the latest version of pandas.
I have confirmed this bug exists on the main branch of pandas.
Reproducible Example
Issue Description
When users don't specify indexes, pandas infers the index type for them. It infers to be a
RangeIndex
, except when the frame/series is emtpy, then the index is inferred to be aIndex[object]
.The type of index should be consistently RangeIndex, when users don't declare the index. Same for columns.
Expected Behavior
Empty frames/series should have index/columns like
RangeIndex(0)
instead an empty object index.Found working on #49560.
Installed Versions
NSTALLED VERSIONS
commit : 527be72
python : 3.9.7.final.0
python-bits : 64
OS : Darwin
OS-release : 21.6.0
Version : Darwin Kernel Version 21.6.0: Wed Aug 10 14:28:35 PDT 2022; root:xnu-8020.141.5~2/RELEASE_ARM64_T8101
machine : arm64
processor : arm
byteorder : little
LC_ALL : None
LANG : None
LOCALE : None.UTF-8
pandas : 2.0.0.dev0+593.g527be722a2
numpy : 1.23.3
pytz : 2022.1
dateutil : 2.8.2
setuptools : 65.5.0
pip : 22.2.2
Cython : 0.29.32
pytest : 7.1.2
hypothesis : 6.37.0
sphinx : 5.0.2
blosc : 1.10.6
feather : None
xlsxwriter : None
lxml.etree : 4.9.1
html5lib : None
pymysql : 1.0.2
psycopg2 : 2.9.3
jinja2 : 3.1.2
IPython : 7.29.0
pandas_datareader: None
bs4 : 4.11.1
bottleneck : None
brotli :
fastparquet : 0.8.3
fsspec : 2022.10.0
gcsfs : None
matplotlib : 3.5.2
numba : 0.56.4
numexpr : 2.8.3
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : 10.0.0
pyreadstat : None
pyxlsb : None
s3fs : 2022.10.0
scipy : 1.9.1
snappy : None
sqlalchemy : None
tables : 3.7.0
tabulate : 0.9.0
xarray : None
xlrd : None
zstandard : 0.18.0
tzdata : None
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