检查python中列表的元素中是否存在列表中的任何元素

Question

I'm trying to parse a log file for certain occurrences. As the log file can be quiet big it is necessary to filter out the lines that are of no interest for the application we need it for. the idea was that I make one list with the 4 or 5 strings that I want to look for and then loop over the lines in an other list that contains the lines that I have retained of the log file.

The log file is the log of a proxy and is used to get a view of where requests come from The first reduction was easy by looking for "GET /" in the line and only store the ones that do have that in it.

with open('logfile', 'r') as f:
    for line in f:
        if "GET /" in line:
           lines.append(line)

The list 'lines' needs then to be reduce to the lines that contain one of a number of strings in the url

l1 = ['/Treintickets/aankopen', '/booking/Tickets', '/Acheter/Billets', ...]

I tried list comprehension but that did not work:

result = [l for l in lines if l1 in l]

Is there a way to get this to work without having to loop over the big list lines for each member of 'l1'?

Answer 1

You can use the built-in function any :

result = [line for line in lines if any(substring in line for substring in l1)]

Or, you might consider to use a regex for this.

Answer 2

Wim's answer is excellent and does specify the correct way to fix the comprehension.

Though, I would suggest using a generator expression rather than a comprehension if the input text file is very big! This will prevent Python from loading the entire file into memory.

with open(<file>, "r") as fin:
    generator = (line for line in fin if any(substr in line for substr in l1))
    for res in generator:
         # Handle result found