Return string within a string based on expression 'x={(.*)}'

Question

I have a string that can vary but will always contain x={stuffNeeded}.

For example: n=1,x={y,z,w},erore={3,4,5} or x={y,z,w} or erore={3,4,5},x={y,z,w} etc.

I am having a devil of a time figuring out how to get y,z,w. The closest I got to finding the answer was based off of Yatharth's answer on this other post Regular expression to return all characters between two special characters.

It my searching I've so far come across something that almost worked. Testing was done here http://rubular.com/r/bgixv2J6yF and in python.

This was tested in python using:

i='n=1,x={y,z,w},erore={3,4,5}'
j='n=1,x={y,z,w}'
print re.search('x={(.*)}',i).group(1)
print re.search('x={(.*)}',j).group(1)
print re.search('x={(.*)}.',i).group(1)
print re.search('x={(.*)}.',j).group(1)

Result for the four different print:

'y,z,w'
'y,z,w},erore={3,4,5'
AttributeError: 'NoneType' object has no attribute 'group'
'y,z,w'

Needed result is 'y,z,w' for all cases and then if x={*} really isn't found I would put an error catch.

Thank you in advance.

Upvoted for the phrase "a devil of a time" :D – Tom Dalton Oct 25 '17 at 15:38 — Tom Dalton, Oct 25 '17 at 15:38
@Ev.Kounis: it sure was a typo. Thanks – Scott G Oct 25 '17 at 15:41 — Scott G, Oct 25 '17 at 15:41

score 6 · Accepted Answer · edited Nov 01 '17 at 06:55

6

This regex does what you're trying to do :

regex = r'x={([^\}]*)}'

Live demo here

Explanation

{([^\}]*) : look for an opening bracket, then look for (and capture) any number of non } characters. So, your group 1 will contain the captured values for x.
}: look for a closing bracket

edited Nov 01 '17 at 06:55

answered Oct 25 '17 at 15:32

Ashish Ranjan

5,523
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score 3 · Answer 2 · answered Oct 25 '17 at 15:32

The main problem is that {(.*)} matches the longest string starting by { and ending by }, which in some cases is y,z,w},erore={3,4,5

You could use non-greedy matching by adding ?. You don't need any other case.

import re

i='n=1,x={y,z,w},erore={3,4,5}'
j='n=1,x={y,z,w}'
expr = 'x={(.*?)}'
print (re.search(expr,i).group(1))
print (re.search(expr,j).group(1))

result:

y,z,w
y,z,w

Kaushik NP · Answer 3 · 2017-10-25T15:52:05.460

Using re.findall :

>>> import re
>>> re.findall('x={[^\}]*}', s)

#driver values :

IN : s = 'n=1,x={y,z,w},erore={3,4,5}'
OUT : ['x={y,z,w}']

IN : s = 'n=1,x={y,z,w}'
OUT : ['x={y,z,w}']

IN : s = 'x={y,z,w}'
OUT : ['x={y,z,w}']

Now to get the value of x, y, z , use split and strip :

>>> l = re.findall('x={[^\}]*}', s)

#if `l` is not empty
>>> out = l[0]
=> 'x={y,z,w}'

>>> y, z, x = out.strip('x={}').split(',')
>>> y, z, x
=> ('y', 'z', 'w')

score 1 · Answer 4 · answered Oct 25 '17 at 15:43

1

You can try this:

import re
s = 'n=1,x={y,z,w},erore={3,4,5}'
final_data = re.findall('=\{(.*?)\}', s)

Output:

['y,z,w', '3,4,5']

answered Oct 25 '17 at 15:43

Ajax1234

69,937
8
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102

Return string within a string based on expression 'x={(.*)}'

4 Answers4