Python 24个常用模块编程必备知识库

import os               # 查看当前工作目录  
print(os.getcwd())      # 创建新目录  
os.mkdir('new_folder')  # 列出指定目录下的文件和子目录  
for item in os.listdir('.'):  
print(item)  

import sys           # 输出Python版本信息  
print(sys.version)   # 打印命令行参数  
for arg in sys.argv:  
print(arg)  

from datetime 
import datetime, timedelta  
# 获取当前日期时间  
now = datetime.now()  
print(now)  
# 计算未来日期  
future_date = now + timedelta(days=30)  
print(future_date)  

import math    
# 计算圆面积  
radius = 5  
area = math.pi * radius ##  2  
print(area)    
# 计算最大公约数  
num1, num2 = ¾, 21  
gcd = math.gcd(num1, num2)  
print(gcd)  

import random    
# 生成一个[0, 1)之间的随机浮点数  
rand_float = random.random()  
print(rand_float)    
# 随机从列表中选取一个元素  
choices = ['apple', 'banana', 'orange']  
random_choice = random.choice(choices)  
print(random_choice)  

import csv    
# 写入CSV文件  
with open('data.csv', 'w', newline='') as file:  
    writer = csv.writer(file)  
    writer.writerow(['Name', 'Age'])  
    writer.writerow(['Alice', 25])  
# 读取CSV文件  
with open('data.csv', newline='') as file:  
    reader = csv.reader(file)  
    for row in reader:  
    print(row)  

import json    
# 将Python对象转换为JSON字符串  
data = {'name': 'John', 'age': 30}  
json_str = json.dumps(data)  
print(json_str)    
# 从JSON字符串解析回Python对象  
loaded_data = json.loads(json_str)  
print(loaded_data)  

import requests    
# 发送GET请求并打印响应内容  
response = requests.get('https://api.github.com')  
print(response.text)  

import pandas as pd    
# 从CSV文件加载数据到DataFrame  
df = pd.read_csv('data.csv')    
# 查看前5行数据  
print(df.head())  

import numpy as np    
# 创建一个2x2的数组  
arr = np.array([[1, 2], [3, 4]])  
print(arr)    
# 计算数组元素之和  
sum_arr = np.sum(arr)  
print(sum_arr)  

import matplotlib.pyplot as plt    
# 绘制简单的折线图  
plt.plot([1, 2, 3, 4], [1, 4, 9, 16])  
plt.show()  

from scipy.optimize 
import minimize    
# 定义目标函数  
def f(x):  
return x## 2 + 10*np.sin(x)    
# 使用优化算法找到最小值  
result = minimize(f, x0=0)  
print(result.x)  

import re    
# 使用正则表达式匹配邮箱地址  
pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b'  
text = 'Contact me at alice@example.com or bob@gmail.com'  
matches = re.findall(pattern, text)  
print(matches)  

import threading    
# 定义线程任务  
def thread_task(name):  
    print(f"Thread {name} started.")  
    # ... 执行任务 ...  
    print(f"Thread {name} finished.")    
# 创建并启动两个线程  
t1 = threading.Thread(target=thread_task, args=("Thread 1",))  
t2 = threading.Thread(target=thread_task, args=("Thread 2",))    
t1.start()  
t2.start()    
# 等待所有线程完成  
t1.join()  
t2.join()    
print("All threads finished.")  

import timeit    
# 测试代码块执行时间  
setup = "import math"  
statement = "math.factorial(100)"  
elapsed_time = timeit.timeit(setup=setup, stmt=statement, number=1000)  
print(f"Average execution time: {elapsed_time/1000:.6f} seconds")  

import unittest    
class TestMathFunctions(unittest.TestCase):  
def test_factorial(self):  
self.assertEqual(math.factorial(5), 120)  
def test_gcd(self):  
self.assertEqual(math.gcd(18, 24), 6)    
if __name__ == '__main__':  unittest.main()  

import argparse    
parser = argparse.ArgumentParser(description='Process some integers.')  
parser.add_argument('integers', metavar='N', type=int, nargs='+',  
                   help='an integer for the accumulator')  
parser.add_argument('--sum', dest='accumulate', action='store_const',  
                   const=sum, default=max,  
                   help='sum the integers (default: find the max)')  
args = parser.parse_args()  
print(args.accumulate(args.integers))  

import logging    
logging.basicConfig(level=logging.INFO)  
logger = logging.getLogger(__name__)    
logger.info("This is an informative message.")  
logger.warning("Watch out! This might be a problem.")  

import sqlite3    
conn = sqlite3.connect('example.db')  
cursor = conn.cursor()    
cursor.execute('''CREATE TABLE stocks  
                 (date text, trans text, symbol text, qty real, price real)''')    
cursor.execute("INSERT INTO stocks VALUES ('202.jpg', 'BUY', 'RHAT', 100, 35.14)")    
conn.commit()  
conn.close()  

import hashlib    
message = "Hello, world!".encode()  
digest = hashlib.sha256(message).hexdigest()  
print(digest)  

import xml.etree.ElementTree as ET    
root = ET.Element("root")  
child = ET.SubElement(root, "child", name="element1")  
ET.SubElement(child, "grandchild").text = "Some text"    
tree = ET.ElementTree(root)  
tree.write("output.xml")  

import shutil  
shutil.copyfile('source.txt', 'destination.txt')  
shutil.move('old_file.txt', 'new_file.txt')  
shutil.rmtree('directory_to_remove')  

import itertools    
combinations = itertools.combinations(range(4), 2)  
for combo in combinations:  
print(combo)  

import functools  @functools.lru_cache(maxsize=32)  
def fib(n):  if n < 2:  
return n  
return fib(n-1) + fib(n-2)    
print(fib(10))