How to Correctly Write DataFrame Data to Excel File and Fix "TypeError: to_excel() missing 1 required positional argument: 'excel

Python Pandas is a powerful library for data manipulation and analysis, but like any other tool, it may throw errors that can be challenging for beginners. One common error encountered by users is the “TypeError: to_excel() missing 1 required positional argument: ‘excel_writer’“. This error typically occurs when attempting to export a DataFrame to an Excel file using the `to_excel()` method without specifying the Excel writer. In this article, we will explore the root cause of this error and provide step-by-step solutions with illustrative examples.

Table of Contents

1. Understanding the Error.

The `to_excel()` method in Pandas requires an Excel writer object as a mandatory argument.

The Excel writer is responsible for handling the Excel file, and without it, the function cannot complete the task.
When users forget to provide the ‘excel_writer‘ argument, Python raises the mentioned error.

2. How to Correctly Write Pandas DataFrame to Excel File and Fix the Error.

2.1 Specify the Excel Writer.

To resolve the error, explicitly specify the Excel writer when using the `to_excel()` method.

The Excel writer can be a filename or an ExcelWriter object.

Here’s an example source code:

import pandas as pd

def specify_excel_writer():
    # Create a DataFrame (replace this with your actual DataFrame)
    data = {'Column1': [1, 2, 3], 'Column2': ['A', 'B', 'C']}
    df = pd.DataFrame(data)

    # Specify the Excel writer (replace 'output.xlsx' with your desired filename)
    excel_writer = pd.ExcelWriter('./output/excel-writer-file.xlsx')

    # Use to_excel() with the specified Excel writer
    df.to_excel(excel_writer, index=False)

    # Close the Excel file to save the column data to the file.
    excel_writer.close()

    print('Write to excel file complete.')


if __name__ == "__main__":
    specify_excel_writer()

When you run the above code, it will generate the below output on the console, and it will create an excel file excel-writer-file.xlsx with data frame data set in it.
```
Write to excel file complete.
```

If you meet the error PermissionError: [Errno 13] Permission denied: ‘./output/excel-writer-file.xlsx’ when you run the above code, that means the excel file is opened by other program such as Microsoft Excel, you can close the Microsoft Excel and run the code again to fix it.

Before you can run the example, you need to make sure the Python openpyxl module is installed on your environment, you can run the command pip show openpyxl to check this.

> pip show openpyxl
Name: openpyxl
Version: 3.1.2
Summary: A Python library to read/write Excel 2010 xlsx/xlsm files
Home-page: https://openpyxl.readthedocs.io
Author: See AUTHORS
Author-email: charlie.clark@clark-consulting.eu
License: MIT
Location: c:\users\zhao song\appdata\roaming\python\python39\site-packages
Requires: et-xmlfile
Required-by:

If you do not install the openpyxl module, it will throw the error ModuleNotFoundError: No module named ‘openpyxl’ when you run the example code.

To install the openpyxl module, you can run the command pip install openpyxl.

> pip install openpyxl
Defaulting to user installation because normal site-packages is not writeable
Collecting openpyxl
  Downloading openpyxl-3.1.2-py2.py3-none-any.whl (249 kB)
     ---------------------------------------- 250.0/250.0 kB 143.4 kB/s eta 0:00:00
Collecting et-xmlfile (from openpyxl)
  Downloading et_xmlfile-1.1.0-py3-none-any.whl (4.7 kB)
Installing collected packages: et-xmlfile, openpyxl
Successfully installed et-xmlfile-1.1.0 openpyxl-3.1.2

2.2 Use a Context Manager.

You can also use a context manager (with statement) to ensure proper handling of the Excel writer.

This is a more Pythonic way and automatically takes care of closing the Excel writer:

import pandas as pd


def use_a_context_manager():
    # Create a DataFrame (replace this with your actual DataFrame)
    data = {'Column1': [1, 2, 3], 'Column2': ['Pandas', 'Matplotlib', 'Numpy']}
    df = pd.DataFrame(data)

    print(df)

    # Use a context manager for the Excel writer
    with pd.ExcelWriter('./output/excel-writer-file-1.xlsx') as excel_writer:
        # Use to_excel() within the context manager
        df.to_excel(excel_writer, index=False)

if __name__ == "__main__":
    use_a_context_manager()

Below is the output and it will generate the excel file ./out

   Column1     Column2
0        1      Pandas
1        2  Matplotlib
2        3       Numpy

2.3 Provide a File Path.

If you prefer a concise approach, you can directly provide the file path as an argument to `to_excel()`:

import pandas as pd

def provide_a_file_path():
    # Create a DataFrame (replace this with your actual DataFrame)
    data = {'Column1': [1, 2, 3], 'Column2': ['Python', 'C++', 'Java']}
    df = pd.DataFrame(data)

    # Specify the file path in to_excel()
    df.to_excel('./output/excel-writer-file-2.xlsx', index=False)



if __name__ == "__main__":
    provide_a_file_path()

3. Conclusion.

By explicitly specifying the Excel writer when using the `to_excel()` method, you can overcome the “TypeError: to_excel() missing 1 required positional argument: ‘excel_writer’” issue.

Choose the method that best suits your coding style and preferences, and ensure a smooth export of your DataFrame to an Excel file in Python Pandas.

How to Correctly Write DataFrame Data to Excel File and Fix “TypeError: to_excel() missing 1 required positional argument: ‘excel_writer'” in Python Pandas