How to Output Every nth Row from a CSV in Python Without Using Pandas

Discover an easy way to extract every `nth` row from a CSV file in Python without using Pandas. Perfect for beginners!
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This video is based on the question https://stackoverflow.com/q/68473744/ asked by the user 'Alex' ( https://stackoverflow.com/u/16497034/ ) and on the answer https://stackoverflow.com/a/68473915/ provided by the user 'Jason Riek' ( https://stackoverflow.com/u/5704896/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Extracting Every nth Row from a CSV File in Python

When working with CSV files in Python, you might find yourself needing to extract specific rows for analysis or processing. If you're new to Python, this task may seem daunting, but it's quite simple once you know the right approach. Today, we're going to focus on how to output every nth row from a CSV file without using the Pandas library.

The Challenge

Let's say you've successfully written a script to read and manipulate a CSV file. Now, you want to print or save every 10th row to a new file. This can be particularly useful if your dataset is large and you only need a sample for your analysis or testing purposes.

Here's What You'll Need

Basic understanding of Python.

A CSV file for demonstration.

Python's built-in csv module for reading and writing CSV files.

The Solution

Below, we will provide a complete script that demonstrates how to extract every 10th row from a CSV file using Python's csv module.

Sample Code

Here's how you can implement the solution:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Import Necessary Libraries:

We use csv for handling CSV files and sys for command-line arguments.

Input and Output Filenames:

The input filename is accepted as a command-line argument. The output filename is created based on the input filename, appending '-Skipped.csv’ to it.

Reading and Writing CSV Files:

We open the input file for reading and the output file for writing.

Using csv.reader, we read the input file line by line.

Enumerating Rows:

With enumerate, we track our current row index. The if row % 10 == 0 condition checks whether the row index is a multiple of 10. In this case, every 10th row gets printed and written to the output file.

Final Output:

Finally, a message is printed showing how many rows were formatted.

Conclusion

Now you know how to extract every nth row from a CSV file using Python without any external libraries like Pandas. This can be a handy way to work with large datasets, enabling you to efficiently analyze or present your data with just a few lines of code.

Happy coding, and enjoy exploring the possibilities Python has to offer!