每个数据科学家都应该知道的12个Python特性！

# list comprehension_list = [x**2 for x in range(1, 11)]
# nested list comprehension to flatten listmatrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
flat_list = [num # append to list            for row in matrix # outer loop            for num in row] # inner loop
print(_list)print(flat_list)[1, 4, 9, 16, 25, 36, 49, 64, 81, 100][1, 2, 3, 4, 5, 6, 7, 8, 9]

# dictionary comprehension_dict = {var:var ** 2 for var in range(1, 11) if var % 2 != 0}
# set comprehension# create a set of squares of numbers from 1 to 10_set = {x**2 for x in range(1, 11)}
# generator comprehension_gen = (x**2 for x in range(1, 11))
print(_dict)print(_set)print(list(g for g in _gen)){1: 1, 3: 9, 5: 25, 7: 49, 9: 81}{64, 1, 4, 36, 100, 9, 16, 49, 81, 25}[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

for idx, value in enumerate(["a", "b", "c", "d"]):    if idx % 2 == 0:        print(value)ac

x = [1, 2, 3, 4]y = [5, 6, 7, 8]
# iterate over both arrays simultaneouslyfor a, b in zip(x, y):    print(a, b, a + b, a * b)1 5 6 52 6 8 123 7 10 214 8 12 32

def fib_gen(n):    a, b = 0, 1    for _ in range(n):        yield a        a, b = b, a + b

res = fib_gen(10)print(list(r for r in res))[0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

numbers = range(10)even_numbers = list(filter(lambda x: x % 2 == 0, numbers))print(even_numbers)[0, 2, 4, 6, 8]

import pandas as pd
data = {    "sales_person": ["Alice", "Bob", "Charlie", "David"],    "sale_amount": [100, 200, 300, 400],}df = pd.DataFrame(data)
threshold = 250df["above_threshold"] = df["sale_amount"].apply(    lambda x: True if x >= threshold else False)dfsales_person   sale_amount   above_threshold0   Alice   100   False1   Bob   200   False2   Charlie   300   True3   David   400   True

numbers = range(10)
# Use map(), filter(), and reduce() to preprocess and aggregate the list of numberseven_numbers = filter(lambda x: x % 2 == 0, numbers)squares = map(lambda x: x**2, even_numbers)sum_of_squares = reduce(lambda x, y: x + y, squares)

print(f"Sum of the squares of even numbers: {sum_of_squares}")Sum of the squares of even numbers: 120

data = [1, 3, 5, 7]print(any(x % 2 == 0 for x in data))print(all(x % 2 == 1 for x in data))FalseTrue

import random 
def random_numbers():    while True:        yield random.random()
# Use next() to find the first number greater than 0.9num = next(x for x in random_numbers() if x > 0.9)
print(f"First number greater than 0.9: {num}")First number greater than 0.9: 0.9444805819267413

from collections import defaultdict
count = defaultdict(int)for item in ['a', 'b', 'a', 'c', 'b', 'a']:    count[item] += 1
countdefaultdict(int, {'a': 3, 'b': 2, 'c': 1})

from functools import partial
def add(x, y):    return x + y
increment = partial(add, 1)increment(1)2

rom functools import lru_cache
@lru_cache(maxsize=None)def fibonacci(n):    if n <= 1:        return n    return fibonacci(n - 1) + fibonacci(n - 2)
fibonacci(1e3)4.346655768693743e+208

from dataclasses import dataclass
@dataclassclass Person:    name: str    age: int    city: str
p = Person("Alice", 30, "New York")print(p)Person(name='Alice', age=30, city='New York')