Python: dynamically composed regex not working in finditer

Question

I want to find matching words in a sentence, with the word being dynamically supplied. I wrote the following code which works with the example:

text="Algorithmic detection of misinformation and disinformation Gricean perspectives"
found=re.finditer(r"\bdetection\b", text)
for i in found:
    print("found") #this line prints exactly once

But since I need the target word as input that is not known a-priori, I changed the code like below, and it stopped working:

text="Algorithmic detection of misinformation and disinformation Gricean perspectives"
word="detection" #or passed by other functions etc.
found=re.finditer(r"\b"+word+"\b", text)
for i in found:
    print("found") #this line does not print in this piece of code

How should I correct my code please? Thanks

score 1 · Accepted Answer · answered Aug 07 '19 at 13:45

1

found=re.finditer(r"\b"+word+r"\b", text)
#         raw string here ___^

answered Aug 07 '19 at 13:45

Toto

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does `word` also need to be raw string? – WiseDev Aug 07 '19 at 13:53
Thanks, it works – Ziqi Aug 07 '19 at 13:54

score 1 · Answer 2 · answered Aug 07 '19 at 13:57

Simply with Raw f-strings:

text = "Algorithmic detection of misinformation and disinformation Gricean perspectives"
word = "detection"  # or passed by other functions etc.
pat = re.compile(fr"\b{word}\b")   # precompiled pattern
found = pat.finditer(text)
for i in found:
    print("found")

Python: dynamically composed regex not working in finditer

2 Answers2