How Can I Prevent Blank Lines in Python-Generated CSV Files Opened in Excel?

Avoiding Blank Lines in CSV Files Written with Python

When writing CSV files with Python, blank lines may appear between rows when the resulting file is opened in Microsoft Excel. This article addresses why this issue occurs and provides solutions to suppress the extra blank lines.

Causes of Blank Lines

The problem lies in the way Python handles line endings in CSV files. The csv.writer module controls line endings directly, and by default it appends both a carriage return (r) and a newline (n) to the file, resulting in an extra blank line in Excel.

Solutions for Windows

For Windows systems, the Python file must be opened in untranslated text mode using the newline='' parameter. This parameter tells Python not to translate the default newline character (n) into the Windows-specific newline sequence (rn).

Using the with statement:

with open('/pythonwork/thefile_subset11.csv', 'w', newline='') as outfile:
    writer = csv.writer(outfile)

Using the Path module:

from pathlib import Path

with Path('/pythonwork/thefile_subset11.csv').open('w', newline='') as outfile:
    writer = csv.writer(outfile)

Solutions for Python 2 (Windows and Non-Windows)

For Python 2, use binary mode to open the output file ('wb'), as it prevents Python from translating line endings.

with open('/pythonwork/thefile_subset11.csv', 'wb') as outfile:
    writer = csv.writer(outfile)

Additional Notes

• If writing data to an in-memory buffer using StringIO, the resulting string will contain the translated newline sequence (e.g., 'rn' on Windows). To prevent this, use newline='' when writing the buffer to a file.
• In Python 2, handling Unicode characters in CSV files requires additional workarounds due to the Unicode-related issues. Consider using the third-party unicodecsv module for this purpose.

Documentation Links

• https://docs.python.org/3/library/csv.html#csv.writer
• https://docs.python.org/2/library/csv.html#csv.writer

The above is the detailed content of How Can I Prevent Blank Lines in Python-Generated CSV Files Opened in Excel?. For more information, please follow other related articles on the PHP Chinese website!