有没有办法提高for循环处理列表的速度？

Question

I want to improve the performance of my code. I tried few ways someone adviced before, but the speed of my code is still slow. What can I do instead of trying the way I tried?

My code is here:

matched_word = []
for w in word_list:
    for str_ in dictionary:
        if str_ == w:
            matched_word.append(str_)

There are some points of reference here:

• First, the length of word_list is 160,000, and the length of dictionary is about 200,000.
• Second, I can not use a set of word_list because I want to make a list ( matched_word ) including duplicated words (the element of word_list ).
• Third, the following code is still working slow.

import collections
matched_word = collections.deque
for w in dictionary:
    if w in word_list:
        matched_word.append(w)

• Fourth, the following code is also still working slow.

matched_word = [w for w in word_list if w in dictionary]

Thanks for your help. (Thanks to all people who adviced before too.)

Answer 1

Python use GIL to avoid deadlocks that's why python works only in single thread and that's why in some cases it is too slow. I'll give an example of code that you can implement in your own. So, instead of use threading we'll use multiprocessing, maybe the difference do not change so much but try anyway!

Example code:

from multiprocessing import Pool
import time


COUNTER = 50000000

def count(n):
    while n > 0:
        n -= 1

if __name__ == '__main__':
    pool = Pool(processes=2)  # Here you choose how many processes do you want!
    start = time.time()
    # First parametre: the function; second: the value!
    r1 = pool.apply_async(count, [COUNTER//2]) # It is 2 because I choose 2 processes, but can be more!
    r2 = pool.apply_async(count, [COUNTER//2])
    pool.close()
    pool.join()
    end = time.time()
    print(f'Seconds: {end - start}')

That's it! Take a look in my code and try to use in your own! Maybe it helps!