CODEWITHSUNDEEP
pythondictionarybeautifulsoupweb-crawler
Serious Ruffy
Serious Ruffy

Reputation: 817

Python Dictionary: Key with two values possible?

For a test program I'm crawling a webpage. I'd like to crawl all activites for specifid ID´s which are associated to the respective cities.

For example, my initial code:

RegionIDArray = {522: "London", 4745: "London", 2718: "London", 3487: "Tokio"}

Im now wondering if its possible to sum up all IDs (values) which are related to e.g. London into one key:

RegionIDArray = {522, 4745, 2718: "London}

If I´m trying this, I get no results

My full code so far

RegionIDArray = {522: "London", 4745: "London", 2718: "London", 3487: "Tokio"}

for reg in RegionIDArray:
    r = requests.get("https://www.getyourguide.de/-l" +str(reg) +"/")
    soup = BeautifulSoup(r.content, "lxml")

    g_data = soup.find_all("span", {"class": "intro-title"})
    for item in g_data:
        POI_final = (str(item.text))

        end_final = ("POI: " + POI_final)
        if end_final not in already_printed:
           print(end_final)
           already_printed.add(end_final)

Is there any smart way.Appreciate any feedback.

Upvotes: 1

Views: 89

Answers (3)

Ajax1234
Ajax1234

Reputation: 71471

You can use itertools.groupby:

import itertools
RegionIDArray = {522: "London", 4745: "London", 2718: "London", 3487: "Tokio"}
new_results = {tuple(c for c, _ in b):a for a, b in itertools.groupby(sorted(RegionIDArray.items(), key=lambda x:x[-1]), key=lambda x:x[-1])}

Output:

{(3487,): 'Tokio', (4745, 522, 2718): 'London'}

Upvotes: 0

jpp
jpp

Reputation: 164783

You can do this in 2 steps:

  1. Create a dictionary mapping locations to list of IDs.
  2. Reverse this dictionary, taking care to ensure your keys are hashable.

The first step is optimally processed via collections.defaultdict.

For the second step, you can use either tuple or frozenset. I opt for the latter since it is not clear that ordering is relevant.

from collections import defaultdict

RegionIDArray = {522: "London", 4745: "London", 2718: "London", 3487: "Tokio"}

d = defaultdict(list)

for k, v in RegionIDArray.items():
    d[v].append(k)

res = {frozenset(v): k for k, v in d.items()}

print(res)

{frozenset({522, 2718, 4745}): 'London',
 frozenset({3487}): 'Tokio'}

Upvotes: 2

hyperneutrino
hyperneutrino

Reputation: 5425

What you can do is make a reverse lookup table from the values to all working keys, like so:

def reverse(ids):
    table = {}
    for key in ids:
        if ids[key] not in table:
            table[ids[key]] = []
        table[ids[key]].append(key)
    return table

Upvotes: -1

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