BUG: pandas change in style overrides defaults format for other columns

[lcrmorin]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

import pandas as pd
 
pd.set_option('display.float_format', '{:.2f}'.format)
 
pd.DataFrame(15.22345676543234567,columns=[1,2,3,4,5,6],index=['A','Z','R','T'])#.style.format({1:'{:.2%}'})
 
pd.DataFrame(15.22345676543234567,columns=[1,2,3,4,5,6],index=['A','Z','R','T']).style.format({1:'{:.2%}'})

Issue Description

After setting float default number of decimal place to display to 2, the first exemple works, only showing 2 decimals for all column. However when adding a custom style to only the first columns all other columns are formatted with the default 6 decimals places. This is quite counterproductive as it means if we want to set some format we need to define all format. It would be nice to be able to change only a few formats while the unchanged are set to default.

Expected Behavior

When specifying a format for a given columns, pandas should style use user specified default value for other columns.

Installed Versions

INSTALLED VERSIONS

commit : 0691c5c
python : 3.13.0
python-bits : 64
OS : Windows
OS-release : 11
Version : 10.0.22621
machine : AMD64
processor : Intel64 Family 6 Model 142 Stepping 12, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : fr_FR.cp1252

pandas : 2.2.3
numpy : 2.2.1
pytz : 2024.2
dateutil : 2.9.0.post0
pip : 24.2
Cython : None
sphinx : None
IPython : 8.31.0
adbc-driver-postgresql: None
...
zstandard : None
tzdata : 2024.2
qtpy : None
pyqt5 : None

[arthurlw]

Confirmed this still happens on the latest main. Applying .style.format() to just one column causes the others to fall back to full precision. I’m guessing .style.format() overrides display.float_format entirely, so other columns fall back to default formatting.

[attack68]

Please read the notes section of https://pandas.pydata.org/docs/reference/api/pandas.io.formats.style.Styler.format.html

This is behaving as intended and as described.

Displaying a Dataframe using the Dataframe printer is entirely different to displaying a Styler using the Styler's output methods.

What you should do is this:

import pandas as pd
pd.set_option('styler.format.precision', 3)
pd.DataFrame(15.22345676543234567,columns=[1,2,3,4,5,6],index=['A','Z','R','T']).style.format({1:'{:.2%}'})

[arthurlw]

Thanks for the clarification! I missed that Styler uses its own formatting logic via styler.format.precision instead of display.float_format. Appreciate the doc pointer!

[lcrmorin]

Indeed, behaviour is quite confusing. But I can confirm the proposed code works as expected.