45个Python实用小技巧

今天给大家介绍一个Python备忘单，可以作为学习Python编程的快速参考指南。

无论你是学习基础知识的初学者，亦或是稍有经验的开发人员。

使用这个备忘单不仅可以简化你的编码任务，还能提高你的Python熟练程度。

接下来，就来一起学习下吧~

1、数据类型

int_num = 42
float_num = 3.14
string_var = "Hello, Python!"
bool_var = True

2、变量和赋值

x = 10
y = "Python"

3、列表和元组

my_list = [1, 2, 3, "Python"]
my_tuple = (1, 2, 3, "Tuple")

4、字典

my_dict = {'name': 'John', 'age': 25, 'city': 'Pythonville'}

5、条件语句

if x > 0:
    print("Positive")
elif x == 0:
    print("Zero")
else:
    print("Negative")
for item in my_list:
    print(item)
while condition:
    # code

6、函数

def greet(name="User"):
    return f"Hello, {name}!"
result = greet("John")

7、类和对象

class Dog:
    def __init__(self, name):
        self.name = name
def bark(self):
        print("Woof!")
my_dog = Dog("Buddy")
my_dog.bark()

8、文件处理

with open("file.txt", "r") as file:
    content = file.read()
with open("new_file.txt", "w") as new_file:
    new_file.write("Hello, Python!")

9、异常处理

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("Execution completed.")

10、库和模块

import math
from datetime import datetime
result = math.sqrt(25)
current_time = datetime.now()

11、列表推导式

squares = [x**2 for x in range(5)]

12、匿名函数

add = lambda x, y: x + y
result = add(2, 3)

13、虚拟环境

# 创建一个虚拟环境
python -m venv myenv

# 激活虚拟环境
source myenv/bin/activate  # On Unix or MacOS
myenv\Scripts\activate  # On Windows

# 退出虚拟环境
deactivate

14、安装包管理

# 安装Python库
pip install package_name

# 已安装的Python库列表
pip list

# 创建一个requirements.txt文件
pip freeze > requirements.txt

# 根据requirements.txt安装依赖的Python库
pip install -r requirements.txt

15、JSON数据处理

import json

# 将Python对象转换成JSON
json_data = json.dumps({"name": "John", "age": 25})

# 将JSON转换成Python对象
python_obj = json.loads(json_data)

16、正则表达式

import re
pattern = r'\d+'  # 匹配1个或多个数字
result = re.findall(pattern, "There are 42 apples and 123 oranges.")

17、日期操作

from datetime import datetime, timedelta

current_date = datetime.now()
future_date = current_date + timedelta(days=7)

18、列表操作

numbers = [1, 2, 3, 4, 5]

# 过滤
evens = list(filter(lambda x: x % 2 == 0, numbers))

# 映射
squared = list(map(lambda x: x**2, numbers))

# 减少
from functools import reduce
product = reduce(lambda x, y: x * y, numbers)

19、字典操作

my_dict = {'a': 1, 'b': 2, 'c': 3}

# 获取值
value = my_dict.get('d', 0)

# 字典推导式
squared_dict = {key: value**2 for key, value in my_dict.items()}

20、线程并发

import threading
def print_numbers():
    for i in range(5):
        print(i)
thread = threading.Thread(target=print_numbers)
thread.start()

21、使用Asyncio实现并发

import asyncio
async def print_numbers():
    for i in range(5):
        print(i)
        await asyncio.sleep(1)
asyncio.run(print_numbers())

22、使用Beautiful Soup实现网页爬虫

from bs4 import BeautifulSoup
import requests
url = "https://example.com"
response = requests.get(url)
soup = BeautifulSoup(response.text, 'html.parser')
title = soup.title.text

23、使用Flask实现RESTful API

from flask import Flask, jsonify, request
app = Flask(__name__)

@app.route('/api/data', methods=['GET'])
def get_data():
    data = {'key': 'value'}
    return jsonify(data)
if __name__ == '__main__':
    app.run(debug=True)

24、使用unittest进行单元测试

import unittest

def add(x, y):
    return x + y
class TestAddition(unittest.TestCase):
    def test_add_positive_numbers(self):
        self.assertEqual(add(2, 3), 5)
if __name__ == '__main__':
    unittest.main()

25、与SQLite的数据库交互

import sqlite3
conn = sqlite3.connect('example.db')
cursor = conn.cursor()

# 只需SQL查询
cursor.execute('CREATE TABLE IF NOT EXISTS users (id INTEGER PRIMARY KEY, name TEXT)')

# 提交
conn.commit()

# 关闭链接
conn.close()

26、文件写入和读取

# 保存文件
with open('example.txt', 'w') as file:
    file.write('Hello, Python!')
# 读取文件
with open('example.txt', 'r') as file:
    content = file.read()

27、异常操作

try:
    result = 10 / 0
except ZeroDivisionError as e:
    print(f"Error: {e}")
except Exception as e:
    print(f"Unexpected Error: {e}")
else:
    print("No errors occurred.")
finally:
    print("This block always executes.")

28、JSON数据处理

import json

# 将Python对象转换成JSON
json_data = json.dumps({"name": "John", "age": 25})

# 将JSON转换成Python对象
python_obj = json.loads(json_data)

29、Python修饰符

def decorator(func):
    def wrapper():
        print("Before function execution")
        func()
        print("After function execution")
    return wrapper
@decorator
def my_function():
    print("Inside the function")
my_function()

30、使用枚举

from enum import Enum
class Color(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3
print(Color.RED)

31、集合操作

set1 = {1, 2, 3}
set2 = {3, 4, 5}

# 合并
union_set = set1 | set2

# 交集
intersection_set = set1 & set2

# 差值
difference_set = set1 - set2

32、列表推导式

numbers = [1, 2, 3, 4, 5]

# 偶数的平方
squares = [x**2 for x in numbers if x % 2 == 0]

33、匿名函数

add = lambda x, y: x + y
result = add(3, 5)

34、线程与Concurrent.futures

from concurrent.futures import ThreadPoolExecutor
def square(x):
    return x**2
with ThreadPoolExecutor() as executor:
    results = executor.map(square, [1, 2, 3, 4, 5])

35、使用gettext国际化

import gettext

# 设置语言
lang = 'en_US'
_ = gettext.translation('messages', localedir='locale', languages=[lang]).gettext
print(_("Hello, World!"))

36、虚拟环境

# 创建一个虚拟环境
python -m venv myenv

# 激活虚拟环境
source myenv/bin/activate  # On Unix or MacOS
myenv\Scripts\activate  # On Windows

# 退出虚拟环境
deactivate

37、日期处理

from datetime import datetime, timedelta
now = datetime.now()

# 日期格式化
formatted_date = now.strftime('%Y-%m-%d %H:%M:%S')

# 添加天数
future_date = now + timedelta(days=7)

38、使用字典

my_dict = {'name': 'John', 'age': 30}

# 获取值
age = my_dict.get('age', 25)

# 遍历键和键值
for key, value in my_dict.items():
    print(f"{key}: {value}")

39、正则表达式

import re
text = "Hello, 123 World!"

# 匹配数字
numbers = re.findall(r'\d+', text)

40、迭代器

def square_numbers(n):
    for i in range(n):
        yield i**2
squares = square_numbers(5)

41、与SQLite的数据库交互

import sqlite3

# 链接SQLite数据库
conn = sqlite3.connect('mydatabase.db')
cursor = conn.cursor()

# 执行SQL查询语句
cursor.execute('SELECT * FROM mytable')

42、ZIP文件操作处理

import zipfile
with zipfile.ZipFile('archive.zip', 'w') as myzip:
    myzip.write('file.txt')
with zipfile.ZipFile('archive.zip', 'r') as myzip:
    myzip.extractall('extracted')

43、网页抓取请求和BeautifulSoup

import requests
from bs4 import BeautifulSoup
url = 'https://example.com'
response = requests.get(url)
soup = BeautifulSoup(response.text, 'html.parser')

# 获取网页数据
title = soup.title.text

44、使用smtplib发送邮件

import smtplib
from email.mime.text import MIMEText

# 启动邮件服务
server = smtplib.SMTP('smtp.gmail.com', 587)
server.starttls()

# 登录电子邮件账户
server.login('your_email@gmail.com', 'your_password')

# 发送邮件
msg = MIMEText('Hello, Python!')
msg['Subject'] = 'Python Email'
server.sendmail('your_email@gmail.com', 'recipient@example.com', msg.as_string())

45、使用JSON文件

import json
data = {'name': 'John', 'age': 30}

# 写入JSON文件
with open('data.json', 'w') as json_file:
    json.dump(data, json_file)

# 读取JSON文件
with open('data.json', 'r') as json_file:
    loaded_data = json.load(json_file)