list in list, search in an another list

Question

I have a first list, containing string lists and a second list containing strings. I want that when a string from the first list is found in the second, the string from the second is returned and the search resumes at the next string from the first list.

list1 = [
    ['test', 'string'],
    ['hello', 'world']
    ['good', 'morning','everyone']]

list2 = [
    ['test is here'],
    ['hi everyone'],
    ['world of code']]

If list1[0][0] is in list2[0], then return list2[0] and go to list1[1] (don't want to test list1[0][1]).

I've tried nesting for loops inside other for loops with break and if conditions but can't get the solution.

Answer 1

First, here are some tips for solving problems like this in the future:

First, the format of your input data is pretty strange (in my opinion), so I'd really recommend trying to flatten everything out -- this may or may not be possible depending on the larger structure of your program, so if you can't actually do that, then no big deal. Something like:

list1 = [ ['test', 'string'], ['hello', 'world'], ['good', 'morning', 'everyone'] ]
list2 = ['test is here', 'hi everyone', 'world of code']

is already easier to work with from a data processing standpoint, and that's just from flattening list2.

Second, conceptually, you have to have two loops going on here -- the first is to iterate through list1 (so if you find a match in list2, you can return the match and move onto the next member of list1), and another to go through the individual elements of list1, since a string in list2 could match on any one of the strings from the inner lists in list1 (i.e. a string in list2 could be matched either by 'test' or 'string').

With that said, here's a (pretty inefficient) solution to your problem:

def check_long_str(long_strings, check_list):

    for check in check_list: #iterate over individual strings in each inner list of list1
        for long_string_item in long_strings: #look for a match in list2
            long_string = long_string_item[0] #weird format
            if check in long_string:
                print('"{}" found "{}"'.format(check, long_string))
                return long_string

    return None

def check_for_strings(search_strings, long_strings):

    toReturn = set()
    for search_list in search_strings: #iterate over inner lists of list1
        found_str = check_long_str(long_strings, search_list)
        if found_str is not None:
            toReturn.add(found_str)

    return toReturn

print(check_for_strings(list1, list2))

Output:

"test" found "test is here"
"world" found "world of code"
"everyone" found "hi everyone"
set(['test is here', 'hi everyone', 'world of code'])