Question

I currently have some python code I’d like to port to C++ as it’s currently slower than I’d like it to be. Problem is that I’m using a dictionary in it where the key is a tuple consisting of an object and a string (e.g. (obj, “word”)). How on earth do I write something similar in C++? Maybe my algorithm is horrendous and there is some way I can make it faster without resorting to C++?

The whole algorithm below for clarity’s sake. The dictionary “post_score” is the issue.

def get_best_match_best(search_text, posts):
    """
    Find the best matches between a search query "search_text" and any of the
    strings in "posts".

    @param search_text: Query to find an appropriate match with in posts.
    @type search_text: string
    @param posts: List of candidates to match with target text.
    @type posts: [cl_post.Post]
    @return: Best matches of the candidates found in posts. The posts are ordered
    according to their rank. First post in list has best match and so on.
    @returntype: [cl_post.Post]
    """
    from math import log

    search_words = separate_words(search_text)
    total_number_of_hits = {}
    post_score = {}
    post_size = {}
    for search_word in search_words:
        total_number_of_hits[search_word] = 0.0
        for post in posts:
            post_score[(post, search_word)] = 0.0
            post_words = separate_words(post.text)
            post_size[post] = len(post_words)
            for post_word in post_words:
                possible_match = abs(len(post_word) - len(search_word)) <= 2
                if possible_match:
                    score = calculate_score(search_word, post_word)
                    post_score[(post, search_word)] += score
                    if score >= 1.0:
                        total_number_of_hits[search_word] += 1.0

    log_of_number_of_posts = log(len(posts))
    matches = []
    for post in posts:
       rank = 0.0
       for search_word in search_words:
           rank += post_score[(post, search_word)] * \
                  (log_of_number_of_posts - log(1.0 + total_number_of_hits[search_word]))
       matches.append((rank / post_size[post], post))
    matches.sort(reverse=True)
    return [post[1] for post in matches]

Answer 1

map<pair<..., string>, ...> if you’re hellbent on using C++ for this.