distance_to_philosophy.py

"""Module to compute the distance from every article to Philosophy."""


from collections import defaultdict, deque
from random import choice
import time
from typing import DefaultDict, Dict, Optional, Set

from get_to_philosophy import get_articles, get_edges
from menu import view_results


def get_reverse_edges(edges: Optional[Dict[str, str]] = None) -> DefaultDict[str, Set]:
    """Compute the reverse edges of Wikipedia articles.
    
    That is, return a dictionary that links the title of an article to the set
    of all other articles that link to it.
    """
    if not edges: edges = get_edges()
    reverse_edges = defaultdict(set)
    print("Computing reverse edges...", end="", flush=True)
    for k, v in edges.items():
        reverse_edges[v].add(k)
    print("Done")
    return reverse_edges


def compute_distances(edges: Optional[Dict[str, str]] = None, reverse_edges: Optional[DefaultDict[str, Set]] = None) -> DefaultDict[str, int]:
    """Compute all the distances to Philosophy."""

    if not edges: edges = get_edges()
    if not reverse_edges: reverse_edges = get_reverse_edges(edges)  # store all articles that point to that link
    seen = set()

    distances = defaultdict(lambda:-1)  # keep track of distances in dict (-1 = no link, 0 = Philosophy, 1 = links to Philosophy, etc)
    q = deque()  # keep track of which articles to look at next
    q.append(["Philosophy"])  # start with Philosophy
    counter = 0
    t0 = time.perf_counter()
    while q:
        articles = q.popleft()  # get batch of articles
        print(f"Batch {counter:3} ({len(articles):7} articles to update) ", end="", flush=True)
        next_articles = []
        for article in articles:
            distances[article] += 1
            if reverse_edges[article] and article not in seen: 
                next_articles.extend(reverse_edges[article])
                seen.add(article)
        for a in next_articles:
            distances[a] = distances[article]  # set value to be equal by default (will be incremented on its turn)
        if next_articles: q.append(next_articles)
        counter += 1
        t1 = time.perf_counter()
        print(f"Completed in {t1 - t0:2.4f}s")
        t0 = t1
    
    print(f"Parsed {len(distances)} articles out of {len(edges)} total ({len(distances) / len(edges) * 100:.4f}% of articles link to Philosophy).")
    return distances


def get_unconnected_articles():
    """Retrieve a list of all articles not connected to Philosophy."""

    articles = get_articles()
    distances = compute_distances()
    return [article.title for article in articles if distances[article.title] == -1]


def main():
    """Main method for querying path distances."""

    QUIT_INPUT = 'q'  # the input to close the terminal
    BACK_INPUT = 'b'  # the input to move back one random article from Philosophy
    PICK_BACK_INPUT = 'p'  # the input to move back to a specified article from the given one
    FWRD_INPUT = 'f'  # the input to move forward one to Philosophy
    DIST_INPUT = '#'  # the input to get a random article by its distance to Philosophy
    PICK_DIST_INPUT = '$'  # the input to get a chosen article by its distance to Philosophy

    edges = get_edges()
    reverse_edges = get_reverse_edges(edges)
    distances = compute_distances(edges, reverse_edges)
    print()

    while True:
        user_input = input(f"Enter an article title ({DIST_INPUT}[num]/{PICK_DIST_INPUT}[num] to get random/choose article by distance, {QUIT_INPUT} to quit)\n")
        print()

        if not user_input:
            print("Nothing entered")
            continue

        if user_input.lower() == QUIT_INPUT:
            print("Closing application...")
            return

        if user_input.lower()[0] == DIST_INPUT or user_input.lower()[0] == PICK_DIST_INPUT:
            if not user_input[1:].isnumeric():
                print(f"Error: {user_input[1:]} is not numeric. Please enter a number for length!\n")
                continue
            if int(user_input[1:]) not in distances.values():
                print(f"No articles have length {user_input[1:]} from Philosophy.")
                continue
            print(f"Retrieving articles of length {user_input[1:]}...", end="", flush=True)
            options = [a for a, dist in distances.items() if dist == int(user_input[1:])]
            print("Done")
            if user_input.lower()[0] == PICK_DIST_INPUT: options.sort()
            user_input = choice(options) if user_input.lower()[0] == DIST_INPUT else view_results(options, can_select=True, results_per_page=15)
            if not user_input:
                print(f"No article selected.")
                continue
        elif user_input not in distances:
            print(f"{user_input} either does not link to Philosophy, or is not a valid article title.\n")
            continue        

        print(f"{user_input} is {distances[user_input]} articles away from Philosophy\n")
        article = user_input

        while True:
            user_input = input(
                f"Enter action for {article}\n"
                f"({BACK_INPUT}) Move away from Philosophy by one (random) article\n"
                f"({PICK_BACK_INPUT}) Move away from Philosophy by one (chosen) article\n"
                f"({FWRD_INPUT}) Move towards Philosophy by one article\n"
                f"(*) Go back\n\n"
            )
            print()
            if user_input.lower() == FWRD_INPUT:
                article = edges[article]
                print(f"{article} is {distances[article]} articles away from Philosophy\n")
            elif user_input.lower() == BACK_INPUT or user_input.lower() == PICK_BACK_INPUT:
                if not reverse_edges[article]:
                    print(f"No articles could be found that link to {article}.")
                    continue
                print(f"{len(reverse_edges[article])} articles link to {article}\n")
                options = list(reverse_edges[article])
                if user_input.lower()[0] == PICK_BACK_INPUT: options.sort()
                article = choice(options) if user_input.lower() == BACK_INPUT else view_results(options, can_select=True, results_per_page=15)
                if not article:
                    print(f"No article selected.")
                    continue
                print(f"{article} is {distances[article]} articles away from Philosophy\n")
            else:
                print("Returning to previous menu...\n")
                break


if __name__=='__main__':
    main()