Python - List - unable to detect size

Question

I have a function which is aimed to parse a text file, found a regex match (ip + port) and return a list with unique value:

def parser (file):
    ip_list = []
    pattern = re.compile('[0-9]+(?:\.[0-9]+){3}.port.*')
    for i, line in enumerate(open(file)):
        for match in re.finditer(pattern, line):
            ip_list.append(match.group())
    unique_ip = reduce(lambda l, x: l if x in l else l+[x], ip_list,[])
    return [unique_ip]

This works pretty fine, but for some reason I'm unable to iterate on returned list object and get current size. Example, if I print out

print(parser(file))

and I obtain this output:

[['212.162.82.10 port 80', '212.162.81.10 port 8081']]

I get a list size of 1 (despite there's 2 elements):

print(len(parser(file)))
1

I'm not getting where I'm making mistake. thx

zglin · Accepted Answer · 2019-10-09 15:27:49Z

2

You have an 2 dimensional array with the double brackets [[

Try len(parser(file[0])) instead or update the code by changing return [unique_ip] to return unique_ip

answered Oct 9, 2019 at 15:27

zglin

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Jtcruthers · Accepted Answer · 2019-10-09 15:30:35Z

1

If you notice the output has two brackets, which means a list inside of a list. You're iterating the outermost list, which only has one element: the inner list. So the length really is one.

Instead of returning [unique_ip], just do return unique_ip.

answered Oct 9, 2019 at 15:30

Jtcruthers

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