# swegym / pandas-dev__pandas-53681 - taskset: [swegym](https://harnessreport.com/tasks/swegym.md) - difficulty: hard - category: debugging - language: - runnable from the site: no - agent timeout: 3000s ## Results by harness _none yet_ ## Instruction ``` BUG: inconsistent behavior of DateOffset ### Pandas version checks - [X] I have checked that this issue has not already been reported. - [X] I have confirmed this bug exists on the [latest version](https://pandas.pydata.org/docs/whatsnew/index.html) of pandas. - [X] I have confirmed this bug exists on the main branch of pandas. ### Reproducible Example ```python import pandas as pd df = pd.DataFrame({ 'S':[pd.Timestamp('2019-04-30')], 'A':[pd.DateOffset(months=1)] }) # FIRST TEST >>> df['S'] + 26 * df['A'] 0 2021-06-30 dtype: datetime64[ns] # SECOND TEST >>> df['S'].iloc[0] + 26 * df['A'].iloc[0] Timestamp('2021-06-28 00:00:00') ``` ### Issue Description It seems like multiplying a DateOffset by constant leads to an inconsistent behavior: the first test gives 30/6 while the second 28/6 ### Expected Behavior In any case it should be 2021-06-30 ### Installed Versions <details> INSTALLED VERSIONS ------------------ commit : 66e3805b8cabe977f40c05259cc3fcf7ead5687d python : 3.10.1.final.0 python-bits : 64 OS : Windows OS-release : 10 Version : 10.0.19042 machine : AMD64 processor : Intel64 Family 6 Model 126 Stepping 5, GenuineIntel byteorder : little LC_ALL : None LANG : None LOCALE : Italian_Italy.1252 pandas : 1.3.5 numpy : 1.21.5 pytz : 2021.3 dateutil : 2.8.2 pip : 21.3.1 setuptools : 58.1.0 Cython : None pytest : None hypothesis : None sphinx : None blosc : None feather : None xlsxwriter : None lxml.etree : 4.8.0 html5lib : None pymysql : None psycopg2 : None jinja2 : None IPython : 8.1.1 pandas_datareader: None bs4 : None bottleneck : None fsspec : None fastparquet : None gcsfs : None matplotlib : 3.5.1 numexpr : None odfpy : None openpyxl : 3.0.9 pandas_gbq : None pyarrow : None pyxlsb : None s3fs : None scipy : 1.7.3 sqlalchemy : None tables : None tabulate : None xarray : None xlrd : None xlwt : None numba : None </details> ``` --- Harness Report runs agent harnesses from their GitHub repos on Harbor tasks and records every model call. Every page is also `.md` and `.json`; index: https://harnessreport.com/llms.txt · MCP: https://harnessreport.com/mcp