How to write a Python regular expression to match multiple words anywhere?

Regular expressions provide a powerful way to match multiple specific words anywhere within a string. Python's re module offers several approaches to accomplish this task efficiently.

Using Word Boundaries with OR Operator

The most common approach uses word boundaries (\b) combined with the OR operator (|) to match complete words ?

import re

s = "These are roses and lilies and orchids, but not marigolds or daisies"
r = re.compile(r'\broses\b|\bmarigolds\b|\borchids\b', flags=re.I | re.X)
print(r.findall(s))

['roses', 'orchids', 'marigolds']

Using Alternation Groups

You can simplify the pattern by grouping alternatives within parentheses ?

import re

s = "These are roses and lilies and orchids, but not marigolds or daisies"
words = ['roses', 'marigolds', 'orchids', 'tulips']
pattern = r'\b(' + '|'.join(words) + r')\b'
matches = re.findall(pattern, s, re.IGNORECASE)
print(matches)

['roses', 'orchids', 'marigolds']

Dynamic Pattern Building

For larger word lists, dynamically build the pattern from a list ?

import re

def find_multiple_words(text, word_list):
    pattern = r'\b(?:' + '|'.join(re.escape(word) for word in word_list) + r')\b'
    return re.findall(pattern, text, re.IGNORECASE)

text = "I love roses, orchids, and marigolds but not dandelions"
flowers = ['roses', 'orchids', 'marigolds', 'tulips', 'daisies']
result = find_multiple_words(text, flowers)
print(result)

['roses', 'orchids', 'marigolds']

Key Components

Conclusion

Use word boundaries with the OR operator for simple cases, or build dynamic patterns for flexible word matching. The re.escape() function ensures special characters in your word list are treated literally.