Python: Surrounding part of a string with other strings?

Question

I have a string like this

the gray fox

and I'd like to surround the word gray with the strings <b> and </b>. What is the most effective (and preferred) way to do this in Python?

(Context: I am building an application with a search function and I'd like to highlight the text in the search results that match the text entered by the user)

Grateful for help and with kind regards, Tord

Answer 1

If you only need to do this with one word, use str.replace:

sentence = "the gray fox"
new = sentence.replace('gray', '<b>gray</b>')
print(new) # the <b>gray</b> fox

If you need to do this with more than one word, use re.sub:

from re import sub
sentence = "the gray fox"
new = sub('(gray)', r'<b>\1</b>', sentence)
print(new) # the <b>gray</b> fox