Sorting IP addresses in Python
Say you have a list with a whole bunch strings that represent IP addresses that you want to sort.
>>> ips = ['192.168.1.10', '10.67.160.10', '43.43.0.1', '10.0.0.1', '255.255.255.0', '19.19.0.1', '140.0.0.1', '141.0.0.1', '255.255.255.255', '192.30.30.1', '255.255.255.0', '10.66.91.140', '255.255.255.0', '192.168.1.1','192.168.2.254', '0.0.0.0', '0.0.0.0', '10.66.91.1', '192.30.30.1', ]
>>> sorted(ips)
['0.0.0.0', '0.0.0.0', '10.0.0.1', '10.66.91.1', '10.66.91.140', '10.67.160.10', '140.0.0.1', '141.0.0.1', '19.19.0.1', '192.168.1.1', '192.168.1.10', '192.168.2.254', '192.30.30.1', '192.30.30.1', '255.255.255.0', '255.255.255.0', '255.255.255.0', '255.255.255.255', '43.43.0.1']
As you can see here the sort ordering is a lexicographic on that's based on the string. "10.0.0.1" comes up then later "140.0.0.1" then later "19.19.0.1".
Sorting in order of the octets would be a lot nicer. This is fairly easily achieved if you stored like list of IPs as ipaddress objects:
>>> import ipaddress
>>> sorted([ipaddress.ip_address(addr) for addr in ips])
[IPv4Address('0.0.0.0'), IPv4Address('0.0.0.0'), IPv4Address('10.0.0.1'), IPv4Address('10.66.91.1'), IPv4Address('10.66.91.140'), IPv4Address('10.67.160.10'), IPv4Address('19.19.0.1'), IPv4Address('43.43.0.1'), IPv4Address('140.0.0.1'), IPv4Address('141.0.0.1'), IPv4Address('192.30.30.1'), IPv4Address('192.30.30.1'), IPv4Address('192.168.1.1'), IPv4Address('192.168.1.10'), IPv4Address('192.168.2.254'), IPv4Address('255.255.255.0'), IPv4Address('255.255.255.0'), IPv4Address('255.255.255.0'), IPv4Address('255.255.255.255')]
But if for some reason you wanted to keep strings you can make use of the fact that sorting in Python just requires that the less than operator is defined which it is in the case of ipaddress.IPv4Address. We can therefore use this constructor as a sort key like so:
>>> sorted(ips, key = ipaddress.IPv4Address)
['0.0.0.0', '0.0.0.0', '10.0.0.1', '10.66.91.1', '10.66.91.140', '10.67.160.10', '19.19.0.1', '43.43.0.1', '140.0.0.1', '141.0.0.1', '192.30.30.1', '192.30.30.1', '192.168.1.1', '192.168.1.10', '192.168.2.254', '255.255.255.0', '255.255.255.0', '255.255.255.0', '255.255.255.255']