Python高效开发实战宝典

with open('file.txt",'w') as f:f.write('Hello, World!')with open('file.txt','r') as f:content = f.read()

import osfrom pathlib import Pathfile_path = os.path.join('folder', "file.txt")path = Path('folder')/ 'file.txt' #现代写法

Import zipfilewith zipfile.ZipFile('archive.zip','w')as zipf:     zipf.write('file.txt')with zipfile.ZipFile('archive.zip','r') as zipf:     zipf.extractall('extracted')

squares =[x**2 for x in range(10)]even_squares =[x**2 for x in range(10)if x % 2 == 0]

person ={'name':'Alice','age': 30}name = person.get('name','未知')  #安全获取for key,value in person.items():      print(f"{key}: {value}")

a={1，2，3，4}b={3，4，5，6}Print(a.union(b)) #并集:{1，2，3，4，5，6}print(a.intersection(b)) #交集:{3，4}

name,age ="Alice"，30print(f"{name}今年{age}岁") # f-stringprint("{0}今年{1}岁".format(name, age))

import retext ="联系方式:email@example.com 电话 123-4567"emails=re.findall(r'[\w._%+-]+@[\w.-]+\.[a-zA-Z]{2,}',text)phones=re.findall(r'\d{3}-\d{4}',text)

Import base64encoded = base64.b64encode("Hello".encode())decoded = base64.b64decode(encoded).decode()

import timedef timer(func):    def wrapper(*args,**kwargs):        start = time.time()        result = func(*args, **kwargs)        print(f"耗时:{time.time()- start}秒")        return result    return wrapper  Lambda 表达式  add = lambda x，y:x + y  Sorted_items=sorted(items, key=lambda x:x[1])

def add(a,b, c): return a + b + cvalues =[1，2，3]print(add(*values)) # 解包列表params = {'a':1,'b':2,'c':3}print(add(**params)) #解包字典

from datetime import datetime, timedeltanow = datetime.now()formatted = now.strftime("%Y-%m-%d%H:%M:%S" )print(f"当前时间:{formatted}")

tomorrow = now + timedelta(days=1)Last_week = now - timedelta(weeks=1)time diff = tomorrow - now #计算时间差

Date_str ="2023-01-15"date obj = datetime.strptime(date_str, "%Y-%m-%d" )

Import jsondata ={'name':'Alice','age': 30}json_str = json.dumps(data,indent=2) #转为JSONparsed = json.loads(json_str) #解析JSON

import csvwith open('data.csv', 'w', newline='') as f:     writer = csv.writer(f)     writer.writerows([['Name','Age'],['Alice',25]])with open('data.csv','r')as f:     reader = csv.reader(f)     for row in reader:          print(row)

import xml.etree.ElementTree as ETXml_str ='<root><itemid="1">值</item></root>'root = ET.fromstring(xml str)value = root.find('item').text

import requestsresponse = requests.get('https://api.example.com/data')if response.status_code == 200:data = response.json()

from bs4 import BeautifulSouphtml = requests.get('https://example.com').textsoup = BeautifulSoup(html, 'html.parser')title = soup.title.textlinks = soup.find _all('a')

from urllib.parse import urlparse, urlencodeParsed_url= urlparse("https://example.com/path")params = {''name": ''张三'',"age": 30}query = urlencode(params)

try:  result=10/0  #会引发 ZeroDivisionErrorexcept ZeroDivisionError as e:  print(f"捕获到错误:{e}")except Exception as e  print(f捕获其他错误:{e}")finally:  print("始终执行的代码")

import logginglogging.basicconfig(    level=logging.INFO,    format='%(asctime)s-%(levelname)s-%(message)s',    filename='app.log')logging.info('程序启动')logging.warning('警告信息')logging.error('错误信息')

import threadingdef task(name):    print(f"线程{name}运行中")threads = [threading.Thread(target=task, args=(i,))          for i in range(3)]for t in threads:      t.start()

import asyncioasync def say_hello(delay, name):   a wait asyncio.sleep(delay)   print(f"Hello, {name}")async def main():  await asyncio.gather(      say_hello(1, "Alice")      say_hello(2, "Bob" )      }# asyncio.run(main()) # Python 3.7+

import sqlite3#连接数据库conn = sqlite3.connect('example.db' )cursor = conn.cursor()# 创建表cursor.execute('''CREATE TABLE IF NOT EXISTS users(    id INTEGER PRIMARY KEY,    name TEXT,    age INTEGER)''')

# 插入数据cursor.execute("INSERT INTO users VALUES(?,?,?)",              (1,'Alice',25))conn.commit()#查询数据cursor.execute("SELECT * FROM users WHERE age > ?",(20,))for row in cursor.fetchall():      print(row)conn.close()

class Person:def _init_(self, name, age):    self.name = name    self.age = agedef greet(self):      return f“你好，我是{self.name}"

class Temperature:def _init_(self, celsius):    self. celsius = celsius@propertydef celsius(self):    return self.celsius@propertydef fahrenheit(self):    return self._celsius* 9/5 + 32

class Vector:      def _init_(self,x,y):      self.x,self.y=x，y      def _add_(self, other):            return Vector(self.x+ other.x, self.y + other.y)      def _str_(self):            return f"Vector({self.x},{self.y})"

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

squares =(x**2 for xin range(10)) # 比列表推导省内存

from itertools import cycle,chain, islicecolors = cycle(['红'，'绿'，'蓝']) # 无限循环print(next(colors)，next(colors)) #红 绿combined=chain([1，2]，[3，4])  #连接多个可迭代对象first_5=islice(fibonacci(100)，5)    # 切片迭代器

import pandas as pdimport numpy as npdata = {'Name': ['Alice','Bob', 'charlie'],'Age':[25，30,35],'City':['北京'，'上海'，'广州’]}df = pd.DataFrame(data)

names  = df['Name'] #选择单列subset = df[['Name', 'Age']]  # 选择多列young  = df[df['Age']< 30]  #条件过滤

print(df.describe()) #统计摘要grouped = df.groupby('City').mean() # 分组统计

from PIL import Image, ImageFilter, ImageDrawimg = Image.open('example.jpg')print(f"大小:{img.size}，格式:{img.format}")

resized = img.resize((300，200))rotated = img.rotate(45)blurred = img.filter(ImageFilter.BLUR)cropped = img.crop((100,100,400,400)) #(left,top,right,bottom)

draw = ImageDraw.Draw(img)draw.rectangle((50,50,150,150),outline="red")draw.text((10,10),"Hello", fill="white" )# 保存图像img.save('modified.jpg', quality=95)

import osfrom dotenv import load_dotenvload_dotenv() # 加载.env文件api_key = os.getenv('API KEY','默认值')os.environ['DEBUG']= 'True' #设置环境变量

import argparseparser = argparse.ArgumentParser(description='示例程序')parser.addargument('filename',help='输入文件')parser.add argument('--v','--verbose', action='store true')args = parser.parse_args()

import subprocessresultresult = subprocess.run(['ls','-l'], capture_output=True,text=True)print(result.stdout)

import unittestdef add(a, b): return a + bclass TestMath(unittest.TestCase):      def test add(self):        self.assertEqual(add(1，2)3)        self.assertEqual(add(-1,1),0)      def test add fail(self):        self.assertNotEqual(add(1,1),3)

import time, timeitdef measure():    start = time.time()    result = sum(range(1000000))    print(f"耗时:{time.time()- start}秒")    return result

from functools import lru_cache@lru_cache(maxsize=128)def fibonacci(n):    if n <= 1: return n    return fibonacci(n-1)+ fibonacci(n-2)

from collections import namedtuplePoint = namedtuple('Point',['x','y'])p= Point(3，4)print(p.x，p.y) # 通过名称访问元素

from enum import Enum,autoclass Color(Enum):      RED = 1      GREEN = 2      BLUE = auto() # 自动赋值

from dataclasses import dataclass@dataclass class Product:      name: str      price: float      quantity:int= 0      def total_cost(self)-> float:            return self.price * self.quantity

import hashlibmd5 = hashlib.md5("password".encode()).hexdigest()sha256 = hashlib.sha256("password".encode()).hexdigest()

import hashlib, ossalt = os.urandom(16)hash = hashlib.pbkdf2_hmac(     'sha256', b'password',salt, 100000).hex()

import secretsimport uuidtoken=secrets.token_hex(16) # 32字符的安全随机令牌secure_num=secrets.randbelow(100) # 0-99的安全随机数user_id =uuid.uuid4() #随机UUID