正则表达式以提取特定位置的数字

Question

I'm programming in python and I need a regular expression that will extract the number between | | in these dataset and save the result for reuse. So it should extract 66 from 1st line, 1032 from the 2nd, 1472 from 3rd and so on. I'm new to programming and regular expression. Any help will be much appreciated!

232404811.111146|66|ip:tcp
232404811.111556|1032|ip:udp:data
232404811.112015|1472|ip:tcp:http:data
232404811.112060|1472|ip:tcp:http:data

The data is in a file & I will loop through it line by line.

Answer 1

You don't need a regex:

numbers_list = []
with open(filename) as f:
    for line in f:
        numbers_list.append(line.split("|")[1]

This will split each line on the | character, and take the second field (remember indexing is 0-based).

If you're feeling fancy, do the whole thing in a list comprehension (thanks Padraic ):

with open(filename) as f:
    numbers_list = [line.split("|")[1] for line in f]

Answer 2

To match this with regex use:

^\d+\.\d+\|(\d+)\|.*?$

The match is in capturing group 1