th 319 - Python Script Causes CSV Blank Lines (Duplicate)

Python Script Causes CSV Blank Lines (Duplicate)

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th?q=Writing To Csv With Python Adds Blank Lines [Duplicate] - Python Script Causes CSV Blank Lines (Duplicate)

Are you struggling with blank lines appearing in your CSV files after running a Python script? This issue can be frustrating and time-consuming to fix, especially if you are working with large datasets. But fear not, as this article will explore the reasons behind this problem and provide helpful tips on how to prevent it from occurring.

One of the main causes of blank lines in CSV files is the unintentional duplication of data during the writing process. This can happen when a script is set up to write data to multiple rows or when there are issues with the formatting of the output file. Additionally, some Python libraries used for reading and writing CSV files may also contribute to this issue.

If you’re looking for solutions to this problem, our article has got you covered. We’ll walk you through several approaches that you can use to address this problem, whether you prefer to modify the existing code or use external libraries to improve the script’s functionality. By the end of this article, not only will you have a better understanding of why this issue occurs, but you’ll also be armed with an array of tools and techniques to ensure that your CSV files remain free of blank lines and duplicates.

So what are you waiting for? If you want to improve your Python script’s performance and avoid the headache of dealing with blank lines in your CSV files, read on to learn more. By the end of this article, you’ll be better equipped to tackle any CSV-related challenge that comes your way!

th?q=Writing%20To%20Csv%20With%20Python%20Adds%20Blank%20Lines%20%5BDuplicate%5D - Python Script Causes CSV Blank Lines (Duplicate)
“Writing To Csv With Python Adds Blank Lines [Duplicate]” ~ bbaz

The Problem

If you’ve ever worked with CSV files in Python, you might have come across a perplexing issue: sometimes, running a script on a CSV file would cause it to have blank lines or duplicates. It’s frustrating to deal with, and can make your data difficult to work with, so it’s important to understand what causes this issue and how to avoid it.

The Cause

So, what causes these blank lines or duplicates to appear? The answer lies in the way that the csv module writes to a file. Specifically, when you use the writerows() method to write data to a file, it separates each row with a line break. However, if the last row in your dataset already includes a line break, then using writerows() will add an additional one at the end of the file, causing a blank line to appear. Similarly, if you accidentally call writerows() twice without clearing the file, you’ll get duplicate rows.

A Solution: Use writerow() Instead of writerows()

One solution to this problem is to use the writerow() method instead of writerows(). This means that instead of passing in all of your rows as a list, you’ll pass them in one at a time. This ensures that each row is written to the file with only one line break, so you won’t end up with any extra ones. Of course, this approach requires more code, but it’s worth it to avoid the headache of sorting through duplicated data.

Using writerows(): Clear the File Between Writes

If you’d prefer to continue using writerows() because it’s more efficient, there is a workaround. Before you write to the file for the second time, you should clear it. This means that all of the existing data will be erased, so you won’t end up with duplicates. To do this, simply open the file in ‘w’ mode instead of ‘a’ mode (which appends to the existing file). Then, write your data as usual.

Method Comparison: writerow() vs writerows()

Method Advantages Disadvantages
writerow() Produces a clean, error-free CSV file without duplicates or extra line breaks Requires more code and can be slower for large datasets
writerows() More efficient for large datasets and requires less code Possible duplicates and extra line breaks can appear if not used carefully

A Final Word

While dealing with blank lines or duplicates in CSV files can be frustrating, it’s important to remember that there are solutions available. Whether you choose to use writerow() or continue using writerows() with the added step of clearing the file between writes, you can handle this issue with ease.

Opinion: Use writerow() is More Reliable

In my opinion, for most small to medium-sized datasets, it’s worth using writerow() to avoid any potential issues with duplicates or blank lines. While it requires more code, it’s a more reliable approach that will ensure your data is error-free. However, for very large datasets where performance is a concern, writerows() may still be the best choice – just be sure to clear the file between writes.


Ultimately, the choice between writerow() and writerows() comes down to the size of your dataset and the performance demands of your project. However, with either approach, you can avoid the headache of dealing with CSV files containing blank lines or duplicates.

Thank you for taking the time to read this article about Python Script causing CSV blank lines. We hope that we were able to shed some light on why you may be experiencing duplicate blank lines in your CSV files due to Python Script.

It is important to remember that while Python Script is a powerful tool, it can also have unintended consequences if not used correctly. In the case of CSV files, blank lines can be created when there are multiple newline characters present in the data. This can lead to confusion and errors when working with the data later on.

However, there are ways to avoid these issues. By using built-in Python libraries like csv, you can ensure that your CSV files are properly formatted and free of duplicate blank lines. Additionally, taking care to account for newlines in your data and using the appropriate strategies can help prevent these issues from occurring.

We hope that this article has helped you understand why you may be seeing duplicate blank lines in your CSV files when using Python Script. Remember to always use caution when utilizing powerful tools like Python, and to take care when working with sensitive data. Thank you again for reading!

People Also Ask about Python Script Causes CSV Blank Lines (Duplicate):

  1. What is causing my CSV file to have blank lines or duplicates?
  2. Is there a way to prevent these blank lines or duplicates from appearing in my CSV file?
  3. Can this issue be caused by the way I am writing my Python script?
  4. Are there any specific libraries or functions in Python that can help me avoid this issue?
  5. How can I debug my Python script to identify the source of the problem?


  • The most common cause of blank lines or duplicates in a CSV file generated by a Python script is due to errors in the code that writes to the file.
  • To prevent blank lines or duplicates, ensure that your script is properly structured and that you are not inadvertently writing empty or duplicate data to the CSV file.
  • Yes, the issue can be caused by the way you are writing your Python script. Make sure that you are properly handling your data and that you are not accidentally writing empty or duplicate rows to the file.
  • Python has several built-in libraries and functions that can help you avoid issues with CSV files, such as the csv module. Make sure to review the documentation for these libraries and functions to ensure that you are using them correctly.
  • To debug your Python script, consider using print statements or a debugger to help you identify where the issue is occurring in your code. You may also want to review any error messages or logs that are generated when your script runs.