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BUG: .dt.seconds Discrepancy Between NumPy and PyArrow Timedelta Dtypes #63283
Description
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Reproducible Example
import pandas as pd
duration = pd.Series(
[pd.Timedelta(days=1, hours=2),
pd.Timedelta(hours=5, minutes=30),
pd.Timedelta(minutes=45, seconds=15)],
index=['class_A', 'class_B', 'class_C']
)
# NumPy-backed
print(duration.dt.seconds)
# Output: [7200, 19800, 2715]
# PyArrow-backed
duration_arrow = duration.astype('duration[us][pyarrow]')
print(duration_arrow.dt.seconds)
# Output: [0, 0, 15]Issue Description
There is a discrepancy in the behavior of the .dt.seconds accessor between pandas Series with NumPy-backed timedelta64[ns] dtype and PyArrow-backed duration[us][pyarrow] dtype.
Expected Behavior
Expected Behavior:
.dt.seconds should return the number of seconds (modulo 1 day) for both NumPy and PyArrow-backed timedeltas, matching the NumPy behavior.
Actual Behavior:
For PyArrow-backed timedeltas, .dt.seconds appears to modulo 1 minute seconds.
Installed Versions
Details
INSTALLED VERSIONS
commit : 1a3230d
python : 3.11.13
python-bits : 64
OS : Darwin
OS-release : 24.6.0
Version : Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:40 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6041
machine : arm64
processor : arm
byteorder : little
LC_ALL : None
LANG : None
LOCALE : en_US.UTF-8
pandas : 3.0.0rc0
numpy : 2.2.6
dateutil : 2.9.0.post0
pip : None
Cython : 3.2.2
sphinx : None
IPython : 9.8.0
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.14.3
bottleneck : None
fastparquet : None
fsspec : None
html5lib : None
hypothesis : None
gcsfs : None
jinja2 : 3.1.6
lxml.etree : None
matplotlib : 3.10.7
numba : 0.62.1
numexpr : None
odfpy : None
openpyxl : None
psycopg2 : None
pymysql : None
pyarrow : 22.0.0
pyiceberg : None
pyreadstat : None
pytest : None
python-calamine : None
pytz : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlsxwriter : None
zstandard : None
qtpy : None
pyqt5 : None
Activity
jorisvandenbossche commentedon Dec 6, 2025
It should indeed be the number of seconds below 1 day (https://pandas.pydata.org/docs/reference/api/pandas.Series.dt.seconds.html), that is the behaviour that is inherited from stdlib
datetime.timedelta.We also have a
.dt.componentsthat gives a more fine grained partitioning:And indeed the pyarrow dtype gives the values equivalent to the seconds component.
jorisvandenbossche commentedon Dec 6, 2025
Looking at the code and git history, this seems to have been introduced by #58052, to fix the
dt.componentsbehaviour of the pyarrow dtype.@jbrockmendel actually mentioned the wrong behaviour the PR would introduce by changing
.dt.secondsand not only.dt.components.seconds, but then the PR was merged regardless. @mroeschke @St0rmie introducing such inconsistency should maybe have been discussed a bit more?mroeschke commentedon Dec 7, 2025
I would be OK reverting #58052 for 3.0 then
aboderinsamuel commentedon Jul 1, 2026
take
fangchenli commentedon Aug 6, 2026
Closed by #63470
Address review: cache day floor-div, tighten comment, drop redundant …