Statistically plausible random User-Agent string generation.

random-ua.py

user_agents = [
    (30.7, '''Mozilla/4.0 (compatible; MSIE 5.0; Windows NT;)
Mozilla/4.0 (Windows; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.50727)
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; GTB5; SLCC1; .NET CLR 2.0.50727; Media Center PC 5.0; .NET CLR 3.0.04506; InfoPath.2; OfficeLiveConnector.1.3; OfficeLivePatch.0.0)
Mozilla/4.0 (Mozilla/4.0; MSIE 7.0; Windows NT 5.1; FDM; SV1; .NET CLR 3.0.04506.30)
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.0.3705; .NET CLR 1.1.4322; Media Center PC 4.0; .NET CLR 2.0.50727)
Mozilla/4.0 (compatible; MSIE 5.0b1; Mac_PowerPC)
Mozilla/2.0 (compatible; MSIE 4.0; Windows 98)
Mozilla/4.0 (compatible; MSIE 5.01; Windows NT)
Mozilla/4.0 (compatible; MSIE 5.23; Mac_PowerPC)
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; GTB6; Ant.com Toolbar 1.6; MSIECrawler)
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0; Trident/4.0; SLCC1; .NET CLR 2.0.50727; .NET CLR 1.1.4322; InfoPath.2; .NET CLR 3.5.21022; .NET CLR 3.5.30729; MS-RTC LM 8; OfficeLiveConnector.1.4; OfficeLivePatch.1.3; .NET CLR 3.0.30729)
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)
Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; Media Center PC 6.0; InfoPath.3; MS-RTC LM 8; Zune 4.7)
Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; Trident/6.0)
Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; WOW64; Trident/6.0)
Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Win64; x64; Trident/6.0)'''.splitlines()),
    (25.1, '''Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1b3) Gecko/20090305 Firefox/3.1b3 GTB5
Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; ko; rv:1.9.1b2) Gecko/20081201 Firefox/3.1b2
Mozilla/5.0 (X11; U; SunOS sun4u; en-US; rv:1.9b5) Gecko/2008032620 Firefox/3.0b5
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.1.12) Gecko/20080214 Firefox/2.0.0.12
Mozilla/5.0 (Windows; U; Windows NT 5.1; cs; rv:1.9.0.8) Gecko/2009032609 Firefox/3.0.8
Mozilla/5.0 (X11; U; OpenBSD i386; en-US; rv:1.8.0.5) Gecko/20060819 Firefox/1.5.0.5
Mozilla/5.0 (Windows; U; Windows NT 5.0; es-ES; rv:1.8.0.3) Gecko/20060426 Firefox/1.5.0.3
Mozilla/5.0 (Windows; U; WinNT4.0; en-US; rv:1.7.9) Gecko/20050711 Firefox/1.0.5
Mozilla/5.0 (Windows; Windows NT 6.1; rv:2.0b2) Gecko/20100720 Firefox/4.0b2
Mozilla/5.0 (X11; Linux x86_64; rv:2.0b4) Gecko/20100818 Firefox/4.0b4
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2) Gecko/20100308 Ubuntu/10.04 (lucid) Firefox/3.6 GTB7.1
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b7) Gecko/20101111 Firefox/4.0b7
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b8pre) Gecko/20101114 Firefox/4.0b8pre
Mozilla/5.0 (X11; Linux x86_64; rv:2.0b9pre) Gecko/20110111 Firefox/4.0b9pre
Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.0b9pre) Gecko/20101228 Firefox/4.0b9pre
Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.2a1pre) Gecko/20110324 Firefox/4.2a1pre
Mozilla/5.0 (X11; U; Linux amd64; rv:5.0) Gecko/20100101 Firefox/5.0 (Debian)
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0a2) Gecko/20110613 Firefox/6.0a2'''.splitlines()),
    (24.4, '''Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/525.19 (KHTML, like Gecko) Chrome/1.0.154.53 Safari/525.19
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/525.19 (KHTML, like Gecko) Chrome/1.0.154.36 Safari/525.19
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/7.0.540.0 Safari/534.10
Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US) AppleWebKit/534.4 (KHTML, like Gecko) Chrome/6.0.481.0 Safari/534.4
Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US) AppleWebKit/533.4 (KHTML, like Gecko) Chrome/5.0.375.86 Safari/533.4
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.2 (KHTML, like Gecko) Chrome/4.0.223.3 Safari/532.2
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/532.0 (KHTML, like Gecko) Chrome/4.0.201.1 Safari/532.0
Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US) AppleWebKit/532.0 (KHTML, like Gecko) Chrome/3.0.195.27 Safari/532.0
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/530.5 (KHTML, like Gecko) Chrome/2.0.173.1 Safari/530.5
Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.558.0 Safari/534.10
Mozilla/5.0 (X11; U; Linux x86_64; en-US) AppleWebKit/540.0 (KHTML,like Gecko) Chrome/9.1.0.0 Safari/540.0
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/534.14 (KHTML, like Gecko) Chrome/9.0.600.0 Safari/534.14
Mozilla/5.0 (X11; U; Windows NT 6; en-US) AppleWebKit/534.12 (KHTML, like Gecko) Chrome/9.0.587.0 Safari/534.12
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.13 (KHTML, like Gecko) Chrome/9.0.597.0 Safari/534.13
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.11 Safari/534.16
Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/534.20 (KHTML, like Gecko) Chrome/11.0.672.2 Safari/534.20
Mozilla/5.0 (Windows NT 6.0) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/14.0.792.0 Safari/535.1
Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.872.0 Safari/535.2
Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.36 Safari/535.7'''.splitlines()),
    (6.5, '''Mozilla/5.0 (Macintosh; U; PPC Mac OS X; fi-fi) AppleWebKit/420+ (KHTML, like Gecko) Safari/419.3
Mozilla/5.0 (Macintosh; U; PPC Mac OS X; de-de) AppleWebKit/125.2 (KHTML, like Gecko) Safari/125.7
Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en-us) AppleWebKit/312.8 (KHTML, like Gecko) Safari/312.6
Mozilla/5.0 (Windows; U; Windows NT 5.1; cs-CZ) AppleWebKit/523.15 (KHTML, like Gecko) Version/3.0 Safari/523.15
Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/528.16 (KHTML, like Gecko) Version/4.0 Safari/528.16
Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10_5_6; it-it) AppleWebKit/528.16 (KHTML, like Gecko) Version/4.0 Safari/528.16
Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-HK) AppleWebKit/533.18.1 (KHTML, like Gecko) Version/5.0.2 Safari/533.18.5
Mozilla/5.0 (Windows; U; Windows NT 6.1; sv-SE) AppleWebKit/533.19.4 (KHTML, like Gecko) Version/5.0.3 Safari/533.19.4
Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/533.20.25 (KHTML, like Gecko) Version/5.0.4 Safari/533.20.27'''.splitlines()),
    (2.2, '''Opera/5.11 (Windows 98; U) [en]
Mozilla/4.0 (compatible; MSIE 5.0; Windows 98) Opera 5.12 [en]
Opera/6.0 (Windows 2000; U) [fr]
Mozilla/4.0 (compatible; MSIE 5.0; Windows NT 4.0) Opera 6.01 [en]
Opera/7.03 (Windows NT 5.0; U) [en]
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) Opera 7.10 [en]
Opera/9.02 (Windows XP; U; ru)
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; en) Opera 9.24
Opera/9.51 (Macintosh; Intel Mac OS X; U; en)
Opera/9.70 (Linux i686 ; U; en) Presto/2.2.1
Opera/9.80 (Windows NT 5.1; U; cs) Presto/2.2.15 Version/10.00
Opera/9.80 (Windows NT 6.1; U; sv) Presto/2.7.62 Version/11.01
Opera/9.80 (Windows NT 6.1; U; en-GB) Presto/2.7.62 Version/11.00
Opera/9.80 (Windows NT 6.1; U; zh-tw) Presto/2.7.62 Version/11.01
Opera/9.80 (Windows NT 6.0; U; en) Presto/2.8.99 Version/11.10
Opera/9.80 (X11; Linux i686; U; ru) Presto/2.8.131 Version/11.11'''.splitlines()),
]

#

def normalize_probabilities():
    current_value = 0.0
    result = []
    for a in user_agents:
        result.append(((current_value, current_value + a[0]), a[1]))
        current_value += a[0]
    return result, current_value

_agents, _agents_weight_sum = normalize_probabilities()

def random_user_agent():
    rval = random.random()*_agents_weight_sum
    try:
        agent_family = (a for a in _agents if (rval >= a[0][0] and rval < a[0][1])).next()[1]
    except StopIteration:
        agent_family = _agents[-1][1]
    return random.choice(agent_family)