Задачи по Python и машинному обучению. Страница 20

from operator import attrgetter
class A:
    def __init__(self, x, y):
        self.x = x
        self.y = y
    def __getattr__(self, attr):
        return 1
a = A(2, 3)
vals = attrgetter('x', 'y', 'z')(a)
print(sum(vals))

from operator import itemgetter
dicts = [{"a": 1, "b": 2}, {"a": -1, "b": 3}]
max_ = max(dicts, key=itemgetter("a"))
min_ = min(dicts, key=itemgetter("b"))
print(max_['a'], min_['b'])

from operator import itemgetter
dicts = [{"a": 1, "b": 2}, {"a": -1, "b": 3}]
max_ = max(dicts, key=itemgetter("a"))
min_ = min(dicts, key=itemgetter("b"))
print(max_['a'], min_['b'])

from collections import Counter
l1 = ["a", "a", "b", "c"]
l2 = ["a", "b", "b", "c"]
c1 = Counter(l1)
c2 = Counter(l2)
new_c1 = c1 + c2
new_c2 = c1 - c2
mc1 = new_c1.most_common(1)
mc2 = new_c2.most_common(1)
print(mc1[0][1], mc2[0][1])

letters = ['a', 'b', 'a', 'c', 'd', 'd', 'a']
from collections import Counter
letter_counts = Counter(letters)
top = letter_counts.most_common(2)
print(top[0][1])

a = slice(0, 0, -1)
a.start = 1
s = "abcdef"
print(s[a])

a = slice(10)
print(a.start, a.stop, a.step)

a = slice(-1000, 1100, -99)
s = "abcdef"
print(len(s[a]))

s = "abcdef"
a = slice(-10**99, 10**99)
print(s[a])

s = "abcdef"
a = slice(-1e99, 1e99)
print(len(s[a]))

s = "abcdef"
a = slice(-float('inf'), 1000)
print(len(s[a]))

from string import ascii_lowercase as s
a = slice(-3, 50, 2)
x = a.indices(5)
print(s[x[0]:x[1]:x[2]])

def f(items, key=None):
    s = set()
    for item in items:
        val = item if key is None else key(item)
        if val not in s:
            yield item
            s.add(val)
arr = [1.1, 1.2, 2.1, 3.0]
y = f(arr, key=lambda d: sum([int(x) for x in str(d).split(".")]))
print(*y)