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
import numpy as np
Cols = pd.MultiIndex.from_tuples([("Item", "Type 1", "Class A"), ("Item", "Type 1", "Class B"), ("Item", "Type 2", "Class A"), ("Item", "Type 2", "Class B"), ("Item", "Type 3", None)])
df = pd.DataFrame(np.random.randn(10, 5), columns=Cols)
print(df)
df.to_excel("Test.xlsx")Issue Description
When a level in a MultiIndex is None, the resulting dataframe when exported to excel has an invalid level inserted replacing the None. See Image.
Expected Behavior
I would expect the result from to_excel should reflect the levels in the MultiIndex correctly.
Installed Versions
pd.show_versions()
INSTALLED VERSIONS
commit : 2e218d1
python : 3.10.0.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19044
machine : AMD64
processor : Intel64 Family 6 Model 79 Stepping 1, GenuineIntel
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : English_Australia.1252
pandas : 1.5.3
numpy : 1.22.4
pytz : 2022.2.1
dateutil : 2.8.2
setuptools : 57.4.0
pip : 23.0
Cython : 0.29.32
pytest : 7.2.0
hypothesis : None
sphinx : 4.5.0
blosc : None
feather : None
xlsxwriter : 3.0.1
lxml.etree : 4.9.1
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.1.1
pandas_datareader: None
bs4 : 4.10.0
bottleneck : None
brotli : 1.0.9
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : 3.5.1
numba : None
numexpr : 2.8.4
odfpy : None
openpyxl : 3.1.0
pandas_gbq : None
pyarrow : None
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : 1.8.0
snappy : None
sqlalchemy : None
tables : 3.7.0
tabulate : 0.8.9
xarray : None
xlrd : None
xlwt : 1.3.0
zstandard : 0.17.0
tzdata : None