Python - 用句点替换括号并删除第一个和最后一个句点

Question

I am trying to take an input file with a list of DNS lookups that contains subdomain/domain separators with the string length in parenthesis as opposed to periods. It looks like this:

(8)subdomain(5)domain(3)com(0)
(8)subdomain(5)domain(3)com(0)
(8)subdomain(5)domain(3)com(0)

I would like to replace the parenthesis and numbers with periods and then remove the first and last period. My code currently does this, but leaves the last period. Any help is appreciated. Here is the code:

import re

file = open('test.txt', 'rb')
writer = open('outfile.txt', 'wb')


for line in file:
    newline1 = re.sub(r"\(\d+\)",".",line)  
    if newline1.startswith('.'):
        newline1 = newline1[1:-1]   

    writer.write(newline1)

Answer 1

You can split the lines with \\(\\d+\\) regex and then join with . stripping commas at both ends:

for line in file:
    res =".".join(re.split(r'\(\d+\)', line))
    writer.write(res.strip('.'))

See IDEONE demo

Answer 2

Given that your re.sub call works like this:

> re.sub(r"\(\d+\)",".", "(8)subdomain(5)domain(3)com(0)")
'.subdomain.domain.com.'

the only thing you need to do is strip the resulting string from any leading and trailing . :

> s = re.sub(r"\(\d+\)",".", "(8)subdomain(5)domain(3)com(0)")
> s.strip(".")
'subdomain.domain.com'

---

Full drop in solution:

for line in file:
    newline1 = re.sub(r"\(\d+\)",".",line).strip(".")
    writer.write(newline1)

Answer 3

import re
def repl(matchobj):
    if matchobj.group(1):
        return "."
    else:
        return ""



x="(8)subdomain(5)domain(3)com(0)"
print re.sub(r"^\(\d+\)|((?<!^)\(\d+\))(?!$)|\(\d+\)$",repl,x)

Output: subdomain.domain.com .

You can define your own replace function.

Answer 4

import re

for line in file:
    line = re.sub(r'\(\d\)','.',line)

line = line.strip('.')