Description
Pandas version checks
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I have checked that this issue has not already been reported.
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I have confirmed this bug exists on the latest version of pandas.
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I have confirmed this bug exists on the main branch of pandas.
Reproducible Example
# the contents of 'testorb.csv'
"""
ObjID,FORMAT,q,e,inc,node,argPeri,t_p,epoch
S00000t,COM,0.952105479028,0.504888475701,4.899098347472,148.881068605772,39.949789586436,54486.32292808,54466.0
S000015,COM,0.154159694141,0.938877338769,48.223407545506,105.219186748093,38.658234184755,54736.8815041081,54466.0
S000021,COM,0.281032037287,0.878997705355,24.078642319571,135.007398381801,58.797679973638,54022.4542604236,54466.0
"""
import pandas as pd
df = pd.read_csv("testorb.csv", delim_whitespace=True)
"""
this should 'improperly' load the above .csv, which doesn't have any whitespace, as a single column, but instead it breaks apart the columns along the commas
"""Issue Description
trying to load a comma separated .csv file with the delim_whitespace parameter set to True should cause the file to be loaded as a single column, but instead it reads it as if it was delimited by commas and breaks it "properly" (in our case, not how we expect, because the CI test was expecting a failure to load the required columns when we passed a separator parameter as "whitespace" with the above file ). I tested this in 2.1.0, 2.0.3, and 1.5.3 and in the older versions everything worked as expected, but 2.1.0 loaded it with comma separation.
Expected Behavior
should not breakup the csv based on a comma delimiter when delim_whitespace is set to True.
Installed Versions
INSTALLED VERSIONS
commit : ba1cccd
python : 3.10.12.final.0
python-bits : 64
OS : Darwin
OS-release : 21.6.0
Version : Darwin Kernel Version 21.6.0: Sat Jun 18 17:07:22 PDT 2022; root:xnu-8020.140.41~1/RELEASE_ARM64_T6000
machine : arm64
processor : arm
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8
pandas : 2.1.0
numpy : 1.24.3
pytz : 2022.7
dateutil : 2.8.2
setuptools : 68.0.0
pip : 23.2.1
Cython : 3.0.0
pytest : 7.4.0
hypothesis : None
sphinx : 6.1.3
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.14.0
pandas_datareader : None
bs4 : 4.12.2
bottleneck : 1.3.5
dataframe-api-compat: None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : 3.5.3
numba : 0.57.1
numexpr : 2.8.4
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.11.1
sqlalchemy : None
tables : 3.8.0
tabulate : None
xarray : None
xlrd : None
zstandard : None
tzdata : 2023.3
qtpy : None
pyqt5 : None