Description
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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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(optional) I have confirmed this bug exists on the master branch of pandas.
Problem description
Consider code:
import pandas as pd
pd.read_excel('test.xlsx', index_col=[0, 1], engine='openpyxl')with some special test.xlsx (see below).
According to openpyxl issue #1483 and openpyxl documentation, user (i.e. Pandas) have to call sheet.calculate_dimension(force=True) if any workbook's worksheet is "unsized".
(What is "worksheet is unsized"? It means: the worksheet doesn't have DIMENSION_TAG, see WorkSheetParser.parse_dimensions(). When it checked? On ReadOnlyWorksheet object construction.)
But Pandas doesn't do it.
So, if the worksheet is "unsized", on reading it by read_excel(engine='openpyxl') we try to get sheet data. We iterate rows falling down into openpyxl: 1 -> 2 -> 3 -> 4 (with max_col == None) -> 5 -> 6 (it returns self._max_column == None) -> 7 -> 8 (with max_col == None) -> 9 -> 10 (with max_col == None). And in these lines:
max_col = max_col or row[-1]['column']
row_width = max_col + 1 - min_colwe have: row's cells number (row_width) is individual for each row (row).
Now consider an unsized Excel table (I have a real file but it's private; after saving in LibreOffice it's become sized):
We get sheet data:
[ [`A1`],
[ 'B1', 'B2' ] ]But index_col=[0, 1] suppose to have >=2 cols in each row:
Traceback (most recent call last):
File "test.py", line 6, in <module>
pd.read_excel('test.xlsx', index_col=[0, 1], engine='openpyxl')
File "/home/sasha/miniconda3/lib/python3.7/site-packages/pandas/io/excel/_base.py", line 334, in read_excel
**kwds,
File "/home/sasha/miniconda3/lib/python3.7/site-packages/pandas/io/excel/_base.py", line 888, in parse
**kwds,
File "/home/sasha/miniconda3/lib/python3.7/site-packages/pandas/io/excel/_base.py", line 480, in parse
last = data[offset][col]
IndexError: list index out of range
IMHO, patch could be:
diff --git a/pandas/io/excel/_openpyxl.py b/pandas/io/excel/_openpyxl.py
index c4327316d..3efbf4abc 100644
--- a/pandas/io/excel/_openpyxl.py
+++ b/pandas/io/excel/_openpyxl.py
@@ -536,6 +536,9 @@ class _OpenpyxlReader(_BaseExcelReader):
def get_sheet_data(self, sheet, convert_float: bool) -> List[List[Scalar]]:
data: List[List[Scalar]] = []
+
+ sheet.calculate_dimension(force=True)
+
for row in sheet.rows:
data.append([self._convert_cell(cell, convert_float) for cell in row])(But it may provide some drawbacks).
With this patch, sheet data would be:
[ [`A1`, ''],
[ 'B1', 'B2' ] ]Output of pd.show_versions()
INSTALLED VERSIONS
commit : None
python : 3.7.7.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.42-calculate
machine : x86_64
processor : Intel(R) Core(TM) i5-7200U CPU @ 2.50GHz
byteorder : little
LC_ALL : None
LANG : ru_RU.utf8
LOCALE : ru_RU.UTF-8
pandas : 1.0.3
numpy : 1.18.1
pytz : 2020.1
dateutil : 2.8.1
pip : 20.0.2
setuptools : 46.4.0.post20200518
Cython : 0.29.17
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : 1.2.8
lxml.etree : 4.5.0
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.2
IPython : 7.13.0
pandas_datareader: None
bs4 : None
bottleneck : None
fastparquet : None
gcsfs : None
lxml.etree : 4.5.0
matplotlib : 3.1.3
numexpr : None
odfpy : None
openpyxl : 3.0.3
pandas_gbq : None
pyarrow : None
pytables : None
pytest : None
pyxlsb : None
s3fs : None
scipy : 1.4.1
sqlalchemy : None
tables : None
tabulate : None
xarray : None
xlrd : 1.2.0
xlwt : None
xlsxwriter : 1.2.8
numba : None
Thanks!