Python regex, one word with n characters followed by two words with one char

Question

I need to filter strings that start with a word containing 3 or more characters, followed by exactly two words that have only one character. After these three words, anything can follow.

What I tried is this expression:

pattern = r'\w{3,}\s\w\s\w.*'

but it matches a string apple wrong a b c which is not correct (the word "wrong" has more than one char).

A complete example is here:

import pandas as pd

df = pd.DataFrame({'text': ['apple wrong', 'apple wrong b c','apple a b correct', 'apple a b c correct']})
pattern = r'\w{3,}\s\w\s\w.*'
matches = df['text'].str.contains(pattern, regex=True)
result = df[matches]
print(result)

Add a `^` (beginning of string) or `\b` (word boundary) before the first `\w`: `\b\w{3,}\s\w\s\w.*`. — InSync, May 25 '23 at 16:10
`^` represents the start of the string. This ensures that the matching pattern starts from the beginning of the string. — 99problems, May 25 '23 at 16:15

score 1 · Accepted Answer · answered May 25 '23 at 16:33

1

Adding a ^ at the beginning should solve the problem. It makes sure that the pattern starts from the beginning.

pattern =  r'^\w{3,}\s\w\s\w.*'

answered May 25 '23 at 16:33

Abhyuday Vaish

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This will match last word of any length, not only 1. You need to add `\b` before `.*`. – markalex May 25 '23 at 16:56

Python regex, one word with n characters followed by two words with one char

1 Answers1