Python · Theory

collections module

Theory

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collections adds deque, Counter, namedtuple, defaultdict. deque is a fast queue. Counter counts items. namedtuple is a tiny immutable record.

from collections import Counter; Counter("Asha") shows letter counts. That one line is a real example.

collections module — output — Counter of letters in Asha, then deque [0, 1, 2].

Exam tip

Name three collections types + one use each.

# collections module
from collections import Counter, deque
print(Counter("Asha"))
q = deque([1, 2])
q.appendleft(0)
print(list(q))

collections module — output: Counter of letters in Asha, then deque [0, 1, 2].

DefCollections adds deque, Counter, namedtuple, defaultdict.
RuleFrom collections import Counter; Counter("Asha") shows letter counts.
RememberCollections module — output: Counter of letters in Asha, then deque [0, 1, 2].