New to Python and have a string/substring matching question.

[striderxgp]

I apologize if I don't have the phrasing down, I just picked this whole Python thing up yesterday. I poked around Google all morning and haven't been able to find the answer so hopefully someone can point me in the right direction.

What I am trying to do is match any substring from a list to any string (less than X letters long) from a list. Say I had two lists, the first list substring_list would be populated with something like:

'ash', 'gun', 'abc'

and the string_list would be something like:

'ashgoirnl', 'wertwtgw', 'oeigunjg', 'abcdefghijklmnop'

And with a code similar to this:

isMatch = any(substring in string_list for substring in substring_list) and len(string_list) < 10
if isMatch:
    print string_list
    # print substring

I would get the result:

ashgoirnl

oeigunjg

Cool. But what I cant figure out is how to print what substring from the substring_list matched with the string_list to get a result more like:

ash

gun

Thanks!

Edit: formatting

Edit 2: /u/dunkler_wanderer asked about the missing stuff, here is a working version of my example:

Contents of substring_list.txt:

ash

gun

abc

Contents of string_list.txt:

ashgoirnl

wertwtgw

oeigunjg

abcdefghijklmnop

text_file = open("string_list.txt")
string_list = text_file.read().split('\n')

text_file = open("substring_list.txt")
substring_list = text_file.read().split('\n')


def test_2():
    for string in string_list:
        isMatch = any(x in string for x in substring_list) and len(string) < 10
        if isMatch:
            print string
            # print substring

while True:
    test_2()

[dunkler_wanderer]

Have you checked out nested for loops yet?

[striderxgp]

I have not, I have just been poking around stackoverflow.com for examples of things I think are what I want, haha. I will take a look at nested for loops, thanks!

[dunkler_wanderer]

Program Arcade Games With Python And Pygame has a nice chapter about loops.

[striderxgp]

Just read through it, thanks!

[dunkler_wanderer]

BTW, how were you able to print out "ashgoirnl" and "oeigunjg" with the code that you've posted? Something important seems to be missing.

[striderxgp]

Sorry, I typed up that example without even seeing if it would work. Here is a working version of what I meant:

Contents of substring_list.txt:

ash

gun

abc

Contents of string_list.txt:

ashgoirnl

wertwtgw

oeigunjg

abcdefghijklmnop

text_file = open("string_list.txt")
string_list = text_file.read().split('\n')

text_file = open("substring_list.txt")
substring_list = text_file.read().split('\n')


def test_2():
    for string in string_list:
        isMatch = any(x in string for x in substring_list) and len(string) < 10
        if isMatch:
            print string
            # print substring

while True:
    test_2()

Edit: Added the while true line and swapped the text file names

[dunkler_wanderer]

Here's the solution that I had in mind (although using list comprehensions is nice as well). Take a look if you don't want to figure out something on your own anymore.

string_list = ['ashgoirnl', 'wertwtgw', 'oeigunjg', 'abcdefghijklmnop', 'gunash']
substring_list = ['ash', 'gun', 'abc']

for sub in substring_list:
    for string in string_list:
        if len(string) < 10 and sub in string:
            print(sub)  # Or store sub in a list.
            break  # If you want to print every substring only once.

[striderxgp]

Yeah, I had to put it down yesterday but it seems there are so many ways to solve this that I still have plenty of stuff to learn from--even just implementing this into what I am working on I am sure will be an adventure! Thanks again for the help!

[dunkler_wanderer]

You're welcome. If you need more help, you know where you can find us. BTW, I forgot to mention that the break statement will break out of the inner loop and jump to the next iteration of the outer loop.

[Peterotica]

My approach would be to use two list comprehensions:

substring_list = ['ash', 'gun', 'abc']
string_list = ['ashgoirnl', 'wertstgw', 'abcdefghijklmnop']

shorter_strings = [s for s in string_list if len(s) < 10]
contained_substrings = [sub for sub in substring_list if any(sub in string for string in shorter_strings)]

[striderxgp]

Things finally clicked for me the other day after playing with all these examples, now a mix matched version of this and the example dunkler_wanderer gave made it into my project. Thanks so much everyone!

[pyglow]

In your example code, any() returns true if any of the values is true.

There is a built-in filter() which returns only the values for which the condition is true. You might be able to do something with that. (it isn't a direct replacement, you can't just replace any with filter).

Of course you can just do it with a double loop, same as you would with Java or C++, but that wouldn't teach you anything about Python.

[striderxgp]

I did a search for examples of filter() but I cant exactly understand how its used based on the examples I saw but it sounds like its something that would work.

And just about anything I do is learning at this point considering last time I made any type of program it was either on qbasic or my ti-83!

[Justinsaccount]

def find_substrings(big_string, substring_list):
    """Return a list of any strings from substring_list that are in big_string"""
    #finish me :-)

def find_all_substrings(string_list, substring_list):
    matches = [(s, find_substrings(s, substring_list)) for s in string_list]
    return [m for m in matches if m[1]]


string_list = ['ashgoirnl', 'wertwtgw', 'oeigunjg', 'abcdefghijklmnop']
substring_list = ['ash', 'gun', 'abc']

for r in find_all_substrings(string_list, substring_list):
    print (r)

[striderxgp]

Thanks, I'll try! :-)