Python: Replace for loops with list comprehension

Question

I'm fairly new at python and list comprehensions are not my strong point. However, I need some help reducing a nested for loop into a single statement like a list comprehension. What I have is:

 source_file_list = ['file1', 'file2', 'file3', 'file4', 'file5', 'file6']
 test_file_list = ['file1', 'file3', 'file5']

 for i in range(len(source_file_list)):
    for j in range(len(test_file_list)):
        if test_file_list[j] in source_file_list[i]:
            file_match_list.append(source_file_list[i])
            break

Any help is appreciated, I'm trying to get rid of the "append"

Answer 1

Use set intersections:

source_file_list = ['file1', 'file2', 'file3', 'file4', 'file5', 'file6']
test_file_list = ['file1', 'file3', 'file5']

file_match_list = set(test_file_list).intersection(source_file_list)

print(file_match_list) # {'file5', 'file1', 'file3'}