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
import pandas as pd
from io import StringIO
csv_data = """0,1.992422433360555e-06,0,1.992422433374335e-06,0,0,0,0.01867750880504259,0,0.8,0,0.002722413402762714,0,0.002722413278797551
3e-12,1.992418292306889e-06,3e-12,1.992418292319521e-06,3e-12,0,3e-12,0.01867750887016915,3e-12,0.8,3e-12,0.002722413686257528,3e-12,0.002722413562292257
9.000000000000001e-12,1.992416874989637e-06,9.000000000000001e-12,1.992416875007223e-06,9.000000000000001e-12,0,9.000000000000001e-12,0.01867750900743637,9.000000000000001e-12,0.8,9.000000000000001e-12,0.00272241426436429,9.000000000000001e-12,0.002722414140398993"""
# Use StringIO to create a file-like object from the string
csv_data_io1 = StringIO(csv_data)
csv_data_io2 = StringIO(csv_data)
# Use pandas.read_csv to read from the file-like object
df1 = pd.read_csv(csv_data_io1)
df2 = pd.read_csv(csv_data_io2, header=None)
# assertions
print(df1.columns.tolist())
print(df2.iloc[0].tolist())Issue Description
Columns are incorrectly read from CSV
Expected Behavior
df1.columns.tolist() being the same as df2.iloc[0].tolist()
i.e.: [0.0, 1.992422433360555e-06, 0.0, 1.992422433374335e-06, 0.0, 0.0, 0.0, 0.0186775088050425, 0.0, 0.8, 0.0, 0.0027224134027627, 0.0, 0.0027224132787975]
However, it is:
['0', '1.992422433360555e-06', '0.1', '1.992422433374335e-06', '0.2', '0.3', '0.4', '0.01867750880504259', '0.5', '0.8', '0.6', '0.002722413402762714', '0.7', '0.002722413278797551']
which is not any row in the file
Installed Versions
INSTALLED VERSIONS
commit : bdc79c1
python : 3.9.7.final.0
python-bits : 64
OS : Linux
OS-release : 5.15.133.1-microsoft-standard-WSL2
Version : #1 SMP Thu Oct 5 21:02:42 UTC 2023
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : C.UTF-8
LOCALE : en_US.UTF-8
pandas : 2.2.1
numpy : 1.26.4
pytz : 2023.3.post1
dateutil : 2.8.2
setuptools : 68.2.2
pip : 23.3.1
Cython : None
pytest : 7.4.1
hypothesis : None
sphinx : 5.0.2
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.9.3
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.3
IPython : 8.15.0
pandas_datareader : None
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.12.2
bottleneck : 1.3.7
dataframe-api-compat : None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : 3.8.0
numba : None
numexpr : 2.8.7
odfpy : None
openpyxl : 3.1.2
pandas_gbq : None
pyarrow : None
pyreadstat : None
python-calamine : None
pyxlsb : None
s3fs : None
scipy : 1.11.4
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
zstandard : None
tzdata : 2023.3
qtpy : None
pyqt5 : None