Remove leading zeros in IP address using Python

Question

Remove unnecessary zeros in IP address:

100.020.003.400  ->  100.20.3.400
001.200.000.004  ->  1.200.0.4
000.002.300.000  ->  0.2.300.0   (optional silly test)

My attempt does not work well in all cases:

import re
ip = re.sub('[.]0+', '.', ip_with_zeroes)

There are similar question but for other languages:

• Perl
• SQL

Please provide solutions for both Python v2 and v3.

Answer 1

ip = "100.020.003.400"
print '.'.join(str(int(part)) for part in ip.split('.'))
# 100.20.3.400

Answer 2

Use the netaddr library and then it has the ZEROFILL flag:

import netaddr

ip = "055.023.156.008"

no_zero_ip = netaddr.IPAddress(ip, flags=netaddr.ZEROFILL).ipv4()

# IPAddress('55.23.156.8')

You probably want to change the no_zero_ip result to a string or something else if you don't want the IPAddress type

Answer 3

For prior to 2.6 you can use the string-modulo operator. But let's not talk about that.

This should do it as far back as the format method was introduced (2.6):

'.'.join('{0}'.format(int(i)) for i in ip.split('.'))

Optionally eliminate the index the for python ≥3.3 or ≥2.7 (I think):

'.'.join('{}'.format(int(i)) for i in ip.split('.'))

And for python ≥3.6 only, we get to f-string it up:

'.'.join(f'{int(i)}' for i in ip.split('.'))

If you can use the last, I highly recommend it. It's quite satisfying.

Answer 4

使用捕获组匹配最后一个数字并复制它，以防止替换所有数字。

ip = re.sub(r'\b0+(\d)', r'\1', ip_with_zeroes)

Answer 5

You can split by "." convert to integer and then string, and join by "."

ip = ".".join([str(int(i)) for i in ip.split(".")])

Answer 6

The Easiest way to do this on Python 3.3+ is to use built-in ipaddress module

import ipaddress
print(str(ipaddress.ip_address("127.000.000.1")))

will print

127.0.0.1

But note that, you'll get an ValueError exception on invalid IP addresses. The good part is this also works with IPv6 addresses.