How To Extract Numbers From A String In Python?

In this tutorial, I will explain how to extract numbers from a string in Python. As a data scientist working for a USA-based company, I often encounter strings that contain both text and numbers. In such cases, I need to extract the numbers from the string for further analysis. Then, I explored more about this topic and found some important methods. I will share my findings in this article with examples.

Table of Contents

Extract Numbers from a String in Python

Python provides several ways to extract numbers from a string. Let’s learn some of the most common methods with examples.

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Method 1. Use Regular Expressions (re)

One of the most useful ways to extract numbers from a string is by using regular expressions (regex). The re module in Python allows you to search for specific patterns within a string. Here’s an example:

import re

text = "Emma Watson, born on April 15, 1990, in Paris, moved to Oxford, UK, OX1 2JD in 2010."
numbers = re.findall(r'\d+', text)

print(numbers)

Output:

['15', '1990', '1', '2', '2010']

I have executed the above example code and added the screenshot below.

In this example, re.findall() searches for all occurrences of one or more digits (\d+) in the string and returns them as a list of strings. The r before the pattern indicates a raw string, which avoids issues with escape characters.

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Method 2. Use list comprehension and isdigit()

Another way to extract numbers from a string is by using a combination of list comprehension and the isdigit() method in Python. Here’s an example:

text = "Liam Olivia Noah Emma Oliver Charlotte Elijah Amelia William Sophia James Isabella Benjamin Mia Lucas Ava Henry Evelyn Alexander Harper"
numbers = [int(word) for word in text.split() if word.isdigit()]

print(numbers)

Output:

[]

I have executed the above example code and added the screenshot below.

How to Extract Numbers from a String in Python

In this example, we split the string into a list of words using split(). Then, we use list comprehension to iterate over each word and check if it consists only of digits using isdigit(). If a word is a valid number, we convert it to an integer int() and include it in the resulting list.

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Method 3. Use join() and filter()

You can also use a combination of Python’s join(), filter(), and isdigit() to extract numbers from a string. Here’s an example:

text = "Michael Smith lives at 123 Main St, Anytown, CA 98765, USA."
numbers = ''.join(filter(lambda x: x.isdigit(), text))

print(numbers)

Output:

12398765

I have executed the above example code and added the screenshot below.

Extract Numbers from a String in Python join() and filter()

In this example, filter() is used with a lambda function to select only the characters that are digits using isdigit(). The resulting characters are then joined together into a single string using join().

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Handle Real-World Scenarios

In real-world scenarios, you might encounter more complex strings that require additional processing. For example, consider the following string:

"The new iPhone 13 Pro costs $999, while the iPhone 13 Mini starts at $699. Apple's headquarters is located at One Apple Park Way, Cupertino, CA 95014, USA."

To extract all the numbers from this string, including those with special characters like “$”, you can use a more sophisticated regular expression:

import re

text = "The new iPhone 13 Pro costs $999, while the iPhone 13 Mini starts at $699. Apple's headquarters is located at One Apple Park Way, Cupertino, CA 95014, USA."
numbers = re.findall(r'[$]?\d+', text)

print(numbers)

Output:

['$999', '$699', '95014']

In this example, the regular expression [$]?\d+ matches optional “$” characters followed by one or more digits, allowing you to extract numbers with leading “$” symbols.

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Conclusion

In this tutorial, I have explained how to extract numbers from a string in Python. I discussed some methods including regular expressions, list comprehension with isdigit(), and a combination of join(), filter(), and isdigit(). I also discussed how to handle real-world scenarios.