How can I find all matches in any position in the string using regular expression (re.finditer) in Python?

Question

I am using python regular expression (regex) to find all the matches in any string position (say "GgGAT", frame 1 is Gg.. and frame2 is gG..). I need to used re.finditer method. My code below gives me only "Gg" while I need both "Gg" and "gG";

import re

data="ACGTGgGTT" 
for match in re.finditer(r'GG|gg|Gg|gG', data):
   print (match)

The regex can be trivially simplified to `[Gg][Gg]`, or just use `(r'gg', data, re.IGNORECASE)` — tripleee, Sep 18 '21 at 12:25
Did you try Re.findall or Re.match? Not sure what is your use case. — Tobias Bruckert, Sep 18 '21 at 13:52

score 2 · Accepted Answer · answered Sep 18 '21 at 12:21

2

You can use regex lookahead using ?=... synthax:

re.finditer(r"(?=(GG|gg|Gg|gG))", data)

answered Sep 18 '21 at 12:21

Gilad Green

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Please write the output. – Shayan Sep 18 '21 at 12:41
This worked perfectly :) – Behmah Sep 19 '21 at 23:06
@GiladGreen I gave your answer a vote, but not sure how to do what you suggesting – Behmah Sep 22 '21 at 13:39
@GiladGreen Done! – Behmah Sep 22 '21 at 23:22

Bhagyesh Dudhediya · Answer 2 · 2021-09-18T15:30:25.360

-1

See if this helps:

import re

data="ACGTGgGTTgGg" 
for match in re.finditer(r'GG|gg|Gg|gG', data):
   for i in range(match.start(),match.end()):
       print (data[i]+data[i+1])

Output:

Gg
gG
gG
Gg

edited Sep 18 '21 at 15:30

answered Sep 18 '21 at 12:35

Bhagyesh Dudhediya

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I need to iterate the matches so have to use "finditer" :) – Behmah Sep 18 '21 at 14:28
Have updated the code.. please check if it helps.. – Bhagyesh Dudhediya Sep 18 '21 at 15:30
Thanks, but if you add another nt at the end you see it's not working – Behmah Sep 19 '21 at 23:11
What do you mean by nt? did not get it.. – Bhagyesh Dudhediya Sep 20 '21 at 05:09

Rinshan Kolayil · Answer 3 · 2021-09-18T19:30:21.403

-1

import re
data="ACGTGgGTgGTGGgg" 
matches = re.findall(r'G{2}', data,re.IGNORECASE) # Or re.I
print(matches)
>> ['Gg', 'gG', 'GG', 'gg']

EDIT

import re
data="ACGTGgGTgGTGGgg" 
for match in re.finditer(r'G{2}', data,re.IGNORECASE):
    print(match)
>>> 
<re.Match object; span=(4, 6), match='Gg'>
<re.Match object; span=(8, 10), match='gG'>
<re.Match object; span=(11, 13), match='GG'>
<re.Match object; span=(13, 15), match='gg'>

edited Sep 18 '21 at 19:30

answered Sep 18 '21 at 13:21

Rinshan Kolayil

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I need to iterate the matches so have to use "finditer" :) – Behmah Sep 18 '21 at 14:27

How can I find all matches in any position in the string using regular expression (re.finditer) in Python?

3 Answers3