How to get specific data from a string using pattern

Question

I'm new to python and I have this string:

  row =  <aa>hello</aa><bb>bello</bb><aa>great</aa><cc>today</cc><aa>later</aa><bb>fine</bb>

I need to get all data that is in aa :

hello,great,later

my code is:

 allAA  =[]
 patternAA = "<aa>(.*)</aa>"
 allAA = '\''+(re.search(patternAA, str(row))).groups() +'\','

and I get this result = <aa>hello</aa><bb>bello</bb><aa>great</aa><cc>today</cc><aa>later</aa> How can I get the data I need?

Do you want to use regular `.find()` and `.index()` functions? — Aniketh Malyala, Mar 01 '22 at 06:37
@MichaelButscher I get this error - can only concatenate str (not "tuple") to str — Damkulul, Mar 01 '22 at 06:41
@AniM I would love to use other options to solve it. can you please post an answer with example I'll check it and if it works i'll mark it — Damkulul, Mar 01 '22 at 06:43
[This](https://stackoverflow.com/q/1732348/17769815) might be a relevant read. :) — BrokenBenchmark, Mar 01 '22 at 06:47

score 0 · Answer 1 · answered Mar 01 '22 at 06:50

You can use a .findall() method that lists all matches for your regex expression

import re

row =  "<aa>hello</aa><bb>bello</bb><aa>great</aa><cc>today</cc><aa>later</aa><bb>fine</bb>"
allAA = re.findall(r'<aa>(.*?)</aa>', row)

print(allAA) # ['hello', 'great', 'later']

score 0 · Accepted Answer · answered Mar 01 '22 at 06:50

There are two issues with your code:

You need to use a non-greedy capture group, specified by using ?.
You should use re.findall() to get the captured, groups, rather than re.search().

With these two fixes, we get the following:

import re
row =  "<aa>hello</aa><bb>bello</bb><aa>great</aa><cc>today</cc><aa>later</aa><bb>fine</bb>"
patternAA = re.compile(r"<aa>(.*?)</aa>")
result = re.findall(patternAA, row)

# Prints ['hello', 'great', 'later']
print(result)

How to get specific data from a string using pattern

2 Answers2