How to Extract Complete Numbers from a Text File in Python

Learn how to efficiently extract complete numbers from a text file in Python without using imports. Discover a simple technique using string methods to achieve your goals!
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Extracting Complete Numbers from a Text File in Python

When working with text files in Python, you might encounter situations where you need to extract complete numbers—such as 10 or 15—instead of individual digits like 1, 0, 1, 5. This can be particularly important when your data is formatted in a way that requires accurate representation of numerical values. In this guide, we will explore how to accomplish this task effectively, providing you with a step-by-step guide to ensure that you can retrieve numbers in a clean list format.

The Problem: Fragmented Numbers

Imagine you have a .txt file filled with sentences that contain integers interspersed throughout the text. When you attempt to extract these numbers using a basic method, you end up with a list of single digits that doesn’t accurately reflect the complete numbers. For example:

Input from the text file:

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Current Output:

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Clearly, this is not the desired outcome. We want to extract whole numbers like [10, 15] instead.

The Solution: Extracting Complete Numbers

Step 1: Opening the File

First, we need to open the text file in read mode. This will allow us to access its contents and process it line by line.

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Step 2: Preparing the List

Next, we need to create a list that will store the processed numbers. For this purpose, we’ll initialize processed_list as an empty list.

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Step 3: Extracting the Numbers

Instead of checking each character individually, we can utilize string methods to split each line into words, and then check if the words are digits. Here’s how you can simplify the extraction process:

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This code does the following:

Reads each line from the file.

Splits the line into individual words.

Checks each word to see if it’s a digit using the isdigit() method.

Converts valid digit strings into integers and adds them to the processed_list.

Step 4: Closing the File

Finally, don't forget to close the file after you're done processing it to free up system resources.

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Example Output

After applying the above technique, if your text file contains the numbers 10 and 15, you should be able to print the processed_list and see:

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Conclusion

In this post, we’ve explored how to extract complete numbers from a text file using Python without the need for external libraries or complex regex. By utilizing simple string methods, you can efficiently gather numerical data as needed. This method is straightforward and works well for extracting positive integers. If you need to handle more complex numeric types, like floats or negative numbers, consider exploring Regular Expressions (Regex) for further extraction capabilities.

Happy Coding!