I want to substitute 1st part of the regex matched string. I am using re (regex) package in python for this:
import re
string = 'H12-H121'
sub_string = 'H12'
re.sub(sub_string,"G12",string)
>> G12-G121
Expected Output:
>> G12-H121
-
1do you need to use regex? Why not str.replace?NBlaine– NBlaine2018-04-25 14:45:14 +00:00Commented Apr 25, 2018 at 14:45
Add a comment
|
4 Answers
You should tell engine that you want to do matching and substitution to be done at beginning using ^ anchor:
re.sub('^H12', 'G12', string)
or if you are not sure about string after -:
re.sub('^[^-]+', 'G12', string)
If you only need to replace first occurrence of H12 use parameter count:
re.sub('H12', 'G12', string, count = 1)
^[^-]+ breakdown:
^Match start of input string[^-]+Match one or more character(s) except-
Comments
add a 1 for the count of occurrences to replace to the call to re.sub. what i mean is:
import re
string = 'H12-H121'
sub_string = 'H12'
re.sub(sub_string,"G12",string, 1) #<---- 1 added here
now the output is 'G12-H121' since it only replaces the first match
Comments
You can do this with just a str.replace()
full_string = 'H12-H121'
sub_string = 'H12'
output_string = full_string.replace(sub_string,"G12",1)
print(output_string)
outputs:
G12-H121
Comments
Just add a ^ to the substring re pattern
import re
s1 = 'H12-H121'
pat = r'^H12'
print(re.sub(pat,"G12",s1))
outputs
G12-H121
