BUG: UnboundLocalError: Variable referenced before assignment on df.style.to_latex(clines="all;data")

[tomaarsen]

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• 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()
print(df.style.to_latex(clines="all;data"))

(The same bug exists with clines="skip-last;data")

Issue Description

Running the example above produces:

Traceback (most recent call last):
  File "/workspaces/pandas/demo.py", line 9, in <module>
    print(df.style.to_latex(clines="all;data"))
  File "/workspaces/pandas/pandas/io/formats/style.py", line 1145, in to_latex
    latex = obj._render_latex(
  File "/workspaces/pandas/pandas/io/formats/style_render.py", line 217, in _render_latex
    self._translate_latex(d, clines=clines)
  File "/workspaces/pandas/pandas/io/formats/style_render.py", line 911, in _translate_latex
    data_len = len(row_body_cells) if "data" in clines else 0
UnboundLocalError: local variable 'row_body_cells' referenced before assignment

Here is a permalink to the line that throws the Exception. The issue is somewhat obvious - if the DataFrame is empty, then there are no lines to iterate over, and row_body_cells is never defined.

Expected Behavior

I would expect an empty tabular being printed, e.g.

\begin{tabular}{l}
\end{tabular}

Furthermore, if the DataFrame does have a header, but no rows, then I expect only the header row to be printed, e.g.

import pandas as pd
df = pd.DataFrame(columns=["a", "b"])
print(df.style.to_latex(clines="all;data"))

should produce

\begin{tabular}{lll}
 & a & b \\
\end{tabular}

As of right now, that snippet produces the same exact Exception as the Reproducible Example.

Installed Versions

INSTALLED VERSIONS

commit : a2f5815
python : 3.8.13.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.72-microsoft-standard-WSL2
Version : #1 SMP Wed Oct 28 23:40:43 UTC 2020
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : C.UTF-8
LANG : C.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.5.0.dev0+854.ga2f5815ddc
numpy : 1.22.4
pytz : 2022.1
dateutil : 2.8.2
setuptools : 56.0.0
pip : 22.1.2
Cython : 0.29.30
pytest : 7.1.2
hypothesis : 6.46.11
sphinx : 5.0.1
blosc : 1.10.6
feather : None
xlsxwriter : 3.0.3
lxml.etree : 4.9.0
html5lib : 1.1
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.4.0
pandas_datareader: None
bs4 : 4.11.1
bottleneck : 1.3.4
brotli : None
fastparquet : 0.8.1
fsspec : 2022.5.0
gcsfs : 2022.5.0
matplotlib : 3.5.2
numba : 0.55.2
numexpr : 2.8.1
odfpy : None
openpyxl : 3.0.10
pandas_gbq : None
pyarrow : 8.0.0
pyreadstat : 1.1.6
pyxlsb : None
s3fs : 2022.5.0
scipy : 1.8.1
snappy :
sqlalchemy : 1.4.37
tables : 3.7.0
tabulate : 0.8.9
xarray : 2022.3.0
xlrd : 2.0.1
xlwt : 1.3.0
zstandard : None

[tomaarsen]

take