Python是一种高级编程语言，属于通用编程语言。它是由荷兰人Guido van Rossum在1989年创造的，其语法简单、易读易写，是一种解释型、面向对象、动态数据类型的编程语言，支持多种编程范式，如面向对象、函数式、过程化等。Python在人工智能、数据科学、Web开发、自动化测试等领域广泛应用，拥有丰富的开源库和工具。因为其易学易用的特点，Python已经成为了编程初学者的首选语言之一。
以下是一些Python代码示例：
1、Hello World程序
print("Hello, World!")
2、列表排序
my_list = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5]
sorted_list = sorted(my_list)
print(sorted_list)
3、字符串拼接
name = "John"
age = 23
print("My name is " + name + " and I am " + str(age) + " years old.")
4、文件读取
with open("file.txt", "r") as f:
contents = f.read()
print(contents)
5、数据库连接
import sqlite3
conn = sqlite3.connect('example.db')
c = conn.cursor()
c.execute('''CREATE TABLE stocks
(date text, trans text, symbol text, qty real, price real)''')
conn.commit()
conn.close()
6、爬虫
import requests
from bs4 import BeautifulSoup
url = 'https://www.python.org/'
response = requests.get(url)
soup = BeautifulSoup(response.text, 'html.parser')
print(soup.title.string)
7、数据分析
import pandas as pd
import matplotlib.pyplot as plt
df = pd.read_csv('data.csv')
df.plot(kind='scatter', x='age', y='income')
plt.show()
8、循环结构
for i in range(10):
print(i)
9、函数定义
def add(x, y):
return x + y
result = add(3, 5)
print(result)
10、类定义
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def say_hello(self):
print("Hello, my name is " + self.name)
person = Person("John", 23)
person.say_hello()
11、GUI程序
import tkinter as tk
window = tk.Tk()
window.title("My App")
label = tk.Label(text="Hello, World!")
label.pack()
window.mainloop()
12、图像处理
from PIL import Image
image = Image.open("image.jpg")
image.show()
13、发送邮件
import smtplib
from email.mime.text import MIMEText
msg = MIMEText("Hello, this is a test email.")
msg['Subject'] = 'Test Email'
msg['From'] = 'sender@example.com'
msg['To'] = 'recipient@example.com'
s = smtplib.SMTP('localhost')
s.send_message(msg)
s.quit()
- 时间日期处理
import datetime
now = datetime.datetime.now()
print(now.strftime("%Y-%m-%d %H:%M:%S"))
15、正则表达式
import re
text = "The quick brown fox jumps over the lazy dog."
result = re.findall(r"\b\w{4}\b", text)
print(result)
16、文件写入
with open("file.txt", "w") as f:
f.write("Hello, World!")
17、多线程
import threading
def worker():
print("Worker Thread")
threads = []
for i in range(5):
t = threading.Thread(target=worker)
threads.append(t)
t.start()
for t in threads:
t.join()
18、数据可视化
import matplotlib.pyplot as plt
x = [1, 2, 3, 4, 5]
y = [1, 4, 9, 16, 25]
plt.plot(x, y)
plt.xlabel('X Label')
plt.ylabel('Y Label')
plt.title('My Plot')
plt.show()
19、网络爬虫
import requests
from bs4 import BeautifulSoup
url = 'https://en.wikipedia.org/wiki/Python_(programming_language)'
response = requests.get(url)
soup = BeautifulSoup(response.text, 'html.parser')
title = soup.find('h1', {'id': 'firstHeading'}).text
print(title)
20、机器学习
from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
from sklearn.neighbors import KNeighborsClassifier
iris = load_iris()
X_train, X_test, y_train, y_test = train_test_split(iris['data'], iris['target'], random_state=0)
knn = KNeighborsClassifier(n_neighbors=1)
knn.fit(X_train, y_train)
print(knn.score(X_test, y_test))
21、多进程
import multiprocessing
def worker():
print("Worker Process")
if __name__ == '__main__':
processes = []
for i in range(5):
p = multiprocessing.Process(target=worker)
processes.append(p)
p.start()
for p in processes:
p.join()
22、音频处理
import librosa
audio, sr = librosa.load("audio.wav")
print(librosa.feature.mfcc(audio, sr=sr))
23、数据库操作
import sqlite3
conn = sqlite3.connect('example.db')
c = conn.cursor()
c.execute("INSERT INTO stocks VALUES ('2006-01-05','BUY','RHAT',100,35.14)")
conn.commit()
conn.close()
24、自然语言处理
import nltk
text = "The quick brown fox jumps over the lazy dog."
tokens = nltk.word_tokenize(text)
print(nltk.pos_tag(tokens))
25、人脸识别
import cv2
face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_default.xml')
img = cv2.imread('image.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
faces = face_cascade.detectMultiScale(gray, 1.3, 5)
for (x,y,w,h) in faces:
cv2.rectangle(img,(x,y),(x+w,y+h),(255,0,0),2)
cv2.imshow
26、数据清洗
import pandas as pd
data = pd.read_csv('data.csv')
data.drop_duplicates(inplace=True)
data.fillna(method='ffill', inplace=True)
27、机器视觉
import cv2
cap = cv2.VideoCapture(0)
while True:
ret, frame = cap.read()
cv2.imshow('Frame', frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cap.release()
cv2.destroyAllWindows()
28、网络通信
import socket
HOST = '127.0.0.1'
PORT = 65432
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
s.bind((HOST, PORT))
s.listen()
conn, addr = s.accept()
with conn:
print('Connected by', addr)
while True:
data = conn.recv(1024)
if not data:
break
conn.sendall(data)
29、云计算
import boto3
s3 = boto3.resource('s3')
s3.create_bucket(Bucket='my-bucket')
bucket = s3.Bucket('my-bucket')
bucket.put_object(Key='test.txt', Body=b'Hello, World!')
for obj in bucket.objects.all():
print(obj.key)
30、数学计算
import numpy as np
a = np.array([[1, 2], [3, 4]])
b = np.array([[5, 6], [7, 8]])
print(np.dot(a, b))
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