groupby.quantile() fails with AssertionError · Issue #30289 · pandas-dev/pandas (original) (raw)

Code Sample, a copy-pastable example if possible

Your code here

df = pd.DataFrame(np.array([10*[_%4] for _ in range(100)]))

df.groupby(0).quantile(0.5)

Out[19]:

1 2 3 4 5 6 7 8 9

0

0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

1 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

2 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0

3 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0

df.groupby(0).quantile([0.5,0.99])

AssertionError Traceback (most recent call last) in ----> 1 df.groupby(0).quantile([0.5,0.99])

~/PycharmProjects/netsim_stats/venv/lib/python3.7/site-packages/pandas/core/groupby/groupby.py in quantile(self, q, interpolation) 1950 1951 indices = np.concatenate(arrays) -> 1952 assert len(indices) == len(result) 1953 return result.take(indices) 1954

AssertionError:

df.quantile([0.5,0.99])

0 1 2 3 4 5 6 7 8 9

0.50 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5

0.99 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0

df.groupby(0)[1].quantile(0.5)

0

0 0.0

1 1.0

2 2.0

3 3.0

Name: 1, dtype: float64

df.groupby(0)[1].quantile([0.5,0.99])

AssertionError Traceback (most recent call last) in ----> 1 df.groupby(0)[1].quantile([0.5,0.99])

~/PycharmProjects/netsim_stats/venv/lib/python3.7/site-packages/pandas/core/groupby/groupby.py in quantile(self, q, interpolation) 1950 1951 indices = np.concatenate(arrays) -> 1952 assert len(indices) == len(result) 1953 return result.take(indices) 1954

AssertionError:

Problem description

The above is a constructed minimal example.
I am not sure how much I should elaborate on the "why this is a problem".

groupby.quantile() fails with an assertion error for "larger" dataframes, smaller dataframes seem to work fine.

Expected Output

Output of pd.show_versions()

INSTALLED VERSIONS

commit : None
python : 3.7.5.final.0
python-bits : 64
OS : Linux
OS-release : 5.3.15-200.fc30.x86_64
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : de_DE.UTF-8
LOCALE : de_DE.UTF-8

pandas : 0.25.3
numpy : 1.17.4
pytz : 2019.3
dateutil : 2.8.1
pip : 19.1.1
setuptools : 40.8.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.2.5
html5lib : 1.0.1
pymysql : None
psycopg2 : None
jinja2 : 2.10.1
IPython : 7.2.0
pandas_datareader: None
bs4 : 4.6.3
bottleneck : None
fastparquet : None
gcsfs : None
lxml.etree : 4.2.5
matplotlib : 3.1.2
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
s3fs : None
scipy : 1.1.0
sqlalchemy : None
tables : None
xarray : None
xlrd : None
xlwt : None
xlsxwriter : None