पाठ 41 / 47

collections और itertools

बिल्ट-इन से आगे, विशेष कंटेनर और लूप के लिए निर्माण खंड।

from collections import Counter, defaultdict

words = ["cat", "dog", "cat", "bird", "cat"]
print(Counter(words))   # Counter({'cat': 3, 'dog': 1, 'bird': 1})

groups = defaultdict(list)
groups["fruit"].append("apple")   # no KeyError, list() is auto-created
print(groups)

from itertools import chain, combinations

print(list(chain([1, 2], [3, 4])))          # [1, 2, 3, 4]
print(list(combinations("ABC", 2)))         # [('A','B'), ('A','C'), ('B','C')]