Find a string and replace it with another string with regex?

Question

I have a text file with below format:

Available Text1

Id                = 0005      
 Cause          = ERROR      
 Code     = 307      
 Event Time              = 2020-11-09 10:16:48      
 Severity      = WARNING      
 Severity Code = 5     
 result       = 2015-06-12 10:19:47
 Id                = 0006      
 Cause          = FAILURE      
 Code     = 517      
 Event Time              = 2020-11-09 10:19:47      
 Severity      = MINOR      
 Severity Code = 4 result = noresult 
 ip[10.1.1.1

I want to find result = in each text file and fulfill the value with the IP.

Requested Data

 Id                = 0005      
 Cause          = ERROR      
 Code     = 307      
 Event Time              = 2020-11-09 10:16:48      
 Severity      = WARNING      
 Severity Code = 5     
 result = 10.1.1.1
 Id                = 0006      
 Cause          = FAILURE      
 Code     = 517      
 Event Time              = 2020-11-09 10:19:47      
 Severity      = MINOR      
 Severity Code = 4 
 result = 10.1.1.1
 ip[10.1.1.1

I used the below code, but it only finds no result value and replace it with IP however there is a datetime value (2015-06-12 10:19:47) with comes in another line as the value of result. How can I use a regex to first find any value after result= and then replace it with IP?

for filepath in file_list:
    txt = open(filepath, "r").read()
    txt = txt.replace("noresult", txt.split("ip[")[-1])
    open(filepath, "w").write(txt)

Answer 1

I would suggest to try with str.rfind or str.rsplit along with re.sub:

import re

s = """\
Id                = 0005
 Cause          = ERROR
 Code     = 307
 Event Time              = 2020-11-09 10:16:48
 Severity      = WARNING
 Severity Code = 5
 result       = 2015-06-12 10:19:47
 Id                = 0006
 Cause          = FAILURE
 Code     = 517
 Event Time              = 2020-11-09 10:19:47
 Severity      = MINOR
 Severity Code = 4 result = noresult
 ip[10.1.1.1
"""

# len('ip[') == 3
ip_addr = s[s.rfind('ip[') + 3:].rstrip('\n')
s = re.sub(r'(result\s*=).*', rf'\1 {ip_addr}', s)
print(s)

Out:

Id                = 0005
 Cause          = ERROR
 Code     = 307
 Event Time              = 2020-11-09 10:16:48
 Severity      = WARNING
 Severity Code = 5
 result       = 10.1.1.1
 Id                = 0006
 Cause          = FAILURE
 Code     = 517
 Event Time              = 2020-11-09 10:19:47
 Severity      = MINOR
 Severity Code = 4 result = 10.1.1.1
 ip[10.1.1.1

Answer 2

So you want to replace result=ANYTHING to result=IP. In this case you may use re.sub() with a regular expression that matches every thing after "result=".

import re
re.sub(r"result =[^\n]+","result = ip[10.1.1.1",txt)

The [^\n]+ will match every char in a single line.

To extract the IP from the text and do the replacement:

ip=re.findall(r"\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b",txt)[0]

txt=re.sub(r"result =[^\n]+","result = "+ip)