Performans, Big-O və collections modulu

import timeit

setup = 'data_list = list(range(100_000)); data_set = set(data_list)'
t_list = timeit.timeit('99_999 in data_list', setup=setup, number=200)
t_set = timeit.timeit('99_999 in data_set', setup=setup, number=200_000) / 1000
print(f'list: {t_list * 1000:.2f} ms for 200 lookups')
print(f'set:  {t_set * 1000:.4f} ms for 200 lookups')
print(f'the set is about {t_list / t_set:,.0f} times faster')

import cProfile
import pstats
from functools import lru_cache

def fib(n):
    return n if n < 2 else fib(n - 1) + fib(n - 2)

@lru_cache(maxsize=None)
def fib_cached(n):
    return n if n < 2 else fib_cached(n - 1) + fib_cached(n - 2)

for func in (fib, fib_cached):
    profiler = cProfile.Profile()
    profiler.runcall(func, 20)
    stats = pstats.Stats(profiler).stats
    calls = sum(v[1] for (_, _, name), v in stats.items() if name == func.__name__)
    print(f'{func.__name__}(20): {calls} calls')

from collections import Counter

words = Counter('the cat and the hat and the bat'.split())
print(words.most_common(2))
print(words['the'], words['dog'])

votes = Counter(['plov', 'dolma', 'plov', 'kebab', 'plov', 'dolma'])
print(votes)
print(votes + Counter(['kebab', 'kebab']))

from collections import defaultdict

students = [('Aysel', '9A'), ('Murad', '9B'), ('Leyla', '9A'), ('Elvin', '9B'), ('Nigar', '9A')]
by_class = defaultdict(list)
for name, group in students:
    by_class[group].append(name)
print(dict(by_class))
print(by_class['10C'], len(by_class))

from collections import deque, namedtuple

queue = deque(['Aysel', 'Murad'])
queue.append('Leyla')
queue.appendleft('Elvin')
print(queue.popleft(), queue)

recent = deque(maxlen=3)
for page in ['home', 'lessons', 'python', 'quiz', 'profile']:
    recent.append(page)
print(list(recent))

Point = namedtuple('Point', ['x', 'y'])
p = Point(3, 4)
print(p, p.x, p[1], p._replace(x=10))

from itertools import accumulate, chain, combinations, groupby, pairwise, product

print(list(chain([1, 2], (3, 4), 'ab')))
print(list(accumulate([5, 3, 8, 2])))
print(list(pairwise([10, 12, 15, 11])))
print(list(combinations('ABC', 2)))
print(len(list(product(range(10), repeat=4))))
fruits = sorted(['cherry', 'apple', 'blueberry', 'avocado', 'banana'])
print({k: list(g) for k, g in groupby(fruits, key=lambda w: w[0])})

numbers = [1, 2, 2, 3, 4, 4, 5]
for n in numbers:
    if n % 2 == 0:
        numbers.remove(n)
print(numbers)

numbers = [1, 2, 2, 3, 4, 4, 5]
numbers = [n for n in numbers if n % 2 != 0]
print(numbers)

from collections import Counter
import re

text = '''Python is fast to write. Python is fun.
Fast code is good, but correct code is better.'''
# 1) turn the text into a list of lower-case words
# 2) print the 3 most common words as 'word: count'

ids = [105, 230, 105, 999, 412, 230, 7, 105]
seen = set()
duplicates = set()
# one pass: if an id is already in seen, it is a duplicate

print(sorted(duplicates))
print(len(seen), 'unique ids')