How Can I Dynamically Match Whole Words in Strings Using Regular Expressions?

Match Whole Words Dynamically in Strings Using Regex

To match a whole word in a string, we can utilize dynamic regular expressions. Consider the following scenario:

Words in a sentence are separated by spaces, but punctuation may appear on either side. To identify words in the middle of a string, the following pattern effectively prevents partial word matches and allows punctuation:

match_middle_words = " [^a-zA-Z\d ]{0,}" + word + "[^a-zA-Z\d ]{0,} "

However, this pattern fails to match the first or last word due to the absence of leading or trailing spaces. To address this, we can use additional patterns:

match_starting_word = "^[^a-zA-Z\d]{0,}" + word + "[^a-zA-Z\d ]{0,} "
match_end_word = " [^a-zA-Z\d ]{0,}" + word + "[^a-zA-Z\d]{0,}$"

By combining these patterns, we obtain the following string:

match_string = match_middle_words  + "|" + match_starting_word  +"|" + match_end_word 

This approach ensures that a word is captured only when it is surrounded by non-word characters. Furthermore, it handles words at the beginning and end of a string.

To simplify this process, we can leverage word boundaries, denoted by b. These boundaries match at the start and end of a string, eliminating the need for separate patterns for the first and last word. The following pattern efficiently matches whole words:

match_string = r'\b' + word + r'\b'

This pattern can be easily modified to match a list of words:

words_list = ['word1', 'word2', 'word3']
match_string = r'\b(?:{})'.format('|'.join(words_list))

By utilizing word boundaries, we eliminate the need for three separate patterns and simplify the process of matching whole words in strings using dynamic regex.

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