BUG: last column name is not bold when applying bold font to column names together with hiding index before converting to latex

[yangtzech]

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

df = pd.DataFrame(
    dict(name=['Raphael', 'Donatello'],
         mask=['red', 'purple'],
         weapon=['sai', 'bo staff']
        )
)
print(df.style.hide(axis="index").applymap_index(lambda v: "font-weight: bold;", axis="columns").to_latex(convert_css=True))

Issue Description

I am trying to convert pandas dataframe to latex with column names in bold font at the sam time , with the code above, which results in:

\begin{tabular}{lll}
\bfseries name & \bfseries mask & weapon \\
Raphael & red & sai \\
Donatello & purple & bo staff \\
\end{tabular}

where the last column name is not in bold font.

Expected Behavior

If I do not hide index with:

print(df.style.applymap_index(lambda v: "font-weight: bold;", axis="columns").to_latex(convert_css=True))

the result will be:

\begin{tabular}{llll}
 & \bfseries name & \bfseries mask & \bfseries weapon \\
0 & Raphael & red & sai \\
1 & Donatello & purple & bo staff \\
\end{tabular}

where the last column name is in bold font.

Installed Versions

INSTALLED VERSIONS

commit : 2e218d1
python : 3.8.13.final.0
python-bits : 64
OS : Linux
OS-release : 5.15.0-53-generic
Version : #59~20.04.1-Ubuntu SMP Thu Oct 20 15:10:22 UTC 2022
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : zh_CN.UTF-8
LOCALE : zh_CN.UTF-8

pandas : 1.5.3
numpy : 1.21.5
pytz : 2022.1
dateutil : 2.8.2
setuptools : 58.0.4
pip : 21.2.4
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.6.5
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.6.0
pandas_datareader: None
bs4 : 4.10.0
bottleneck : None
brotli : None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : 3.5.1
numba : 0.55.1
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.8.0
snappy : None
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
zstandard : None
tzdata : 2022.7

[ltauro]

take

[jgarba]

Take

[ltauro]

Hi @jgarba, I already assigned this task to myself yesterday. Would it be okay if I assign it back to myself?

[jgarba]

yup I will unassign myself

[ltauro]

take

[joveyee]

Panda version 2.0.3

Hi, I was facing the same issue, applying background and font color to LaTeX table headers.
when I hide column index , it affected last header cell styling went missing.
I trace the issue down to pandas.io.formats.style_render.py
def _translate_latex(self, d:dict, clines: str | None) -> None:

the issue is when we call hide(axis=0)
sum(self.hide_index_) == 1
visible_index_level_n = index_levels - sum(self.hide_index_) == 0
it causes the self.ctx_columns[r, c - visible_index_level_n] in enumerate(row) to start from 0 instead of -1.

i added the below just after
visible_index_level_n = index_levels - sum(self.hide_index_)
+ if visible_index_level_n == 0:
+ visible_index_level_n = 1

I manage to get the header color with or without hide(axis=0) works fine.
I am not expert enough to go thought all possible scenario like multi-index or group index or hiding multiple columns,
if you guys can fix this that will be great.

[aaronsnoswell]

+1 for this bug! Came across this today

[corbanvilla]

+1 for this, still happening on 2.2.3

[corbanvilla]

@rhshadrach If I submit a PR with the fix above from @joveyee, will you merge it?