sorting - How to sort IP addresses stored in dictionary in Python?

Question

I have a piece of code that looks like this:

ipCount = defaultdict(int)

for logLine in logLines:
    date, serverIp, clientIp = logLine.split(" ")
    ipCount[clientIp] += 1

for clientIp, hitCount in sorted(ipCount.items), key=operator.itemgetter(0)):
    print(clientIp)

and it kind of sorts IP's, but like this:

192.168.102.105
192.168.204.111
192.168.99.11

which is not good enough since it does not recognize that 99 is a smaller number than 102 or 204. I would like the output to be like this:

192.168.99.11
192.168.102.105
192.168.204.111

I found this, but I am not sure how to implement it in my code, or if it is even possible since I use dictionary. What are my options here? Thank you..

Answer 1

You can use a custom key function to return a sortable representation of your strings:

def split_ip(ip):
    """Split a IP address given as string into a 4-tuple of integers."""
    return tuple(int(part) for part in ip.split('.'))

def my_key(item):
    return split_ip(item[0])

items = sorted(ipCount.items(), key=my_key)

The split_ip() function takes an IP address string like '192.168.102.105' and turns it into a tuple of integers (192, 168, 102, 105). Python has built-in support to sort tuples lexicographically.

UPDATE: This can actually be done even easier using the inet_aton() function in the socket module:

import socket
items = sorted(ipCount.items(), key=lambda item: socket.inet_aton(item[0]))