从这几个方面掌握python基本知识点

目前AI很火，agent应用场景也越来越多，那作为AI中，目前比较贴合的语言python我们该如何掌握它呢？python是一种高级、解释型、通用的编程语言，以其简洁的语法和强大的功能而闻名。接下来我将从几个方面来介绍 python 的基础知识。

一、变量与数据类型

基本数据类型

# 整数
age = 25

# 浮点数
height = 1.75

# 字符串
name = "Alice"

# 布尔值
is_student = True

# 空值
result = None

数据类型检查与转换

# 类型检查
print(type(age))  # <class 'int'>
print(type(name))  # <class 'str'>

# 类型转换
num_str = "123"
num_int = int(num_str)
num_float = float(num_str)
str_num = str(123)

二、数据结构

列表 (List)

# 创建列表
fruits = ["apple", "banana", "orange"]
numbers = [1, 2, 3, 4, 5]

# 列表操作
fruits.append("grape")  # 添加元素
fruits.remove("banana")  # 删除元素
fruits[0] = "pear"  # 修改元素

# 列表切片
print(numbers[1:3])  # [2, 3]
print(numbers[:3])   # [1, 2, 3]
print(numbers[2:])   # [3, 4, 5]

元组 (Tuple)

# 创建元组（不可变）
coordinates = (10, 20)
person = ("Alice", 25, "Engineer")

# 访问元素
print(coordinates[0])  # 10

字典 (Dictionary)

# 创建字典
student = {
    "name": "Bob",
    "age": 20,
    "major": "Computer Science"
}

# 字典操作
student["grade"] = "A"  # 添加键值对
print(student["name"])  # 访问值
del student["age"]     # 删除键值对

集合 (Set)

# 创建集合
unique_numbers = {1, 2, 3, 3, 4}  # {1, 2, 3, 4}

# 集合操作
set1 = {1, 2, 3}
set2 = {3, 4, 5}
print(set1.union(set2))      # {1, 2, 3, 4, 5}
print(set1.intersection(set2))  # {3}

三、 控制流程

条件语句

# if-elif-else
score = 85

if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
else:
    grade = "D"

print(f"成绩等级: {grade}")

循环语句

# for 循环
fruits = ["apple", "banana", "orange"]
for fruit in fruits:
    print(fruit)

# 使用 range()
for i in range(5):      # 0, 1, 2, 3, 4
    print(i)

for i in range(1, 6):   # 1, 2, 3, 4, 5
    print(i)

# while 循环
count = 0
while count < 5:
    print(count)
    count += 1

# 循环控制
for i in range(10):
    if i == 3:
        continue  # 跳过本次循环
    if i == 7:
        break     # 终止循环
    print(i)

四、函数

函数定义与调用

# 基本函数
def greet(name):
    return f"Hello, {name}!"

print(greet("Alice"))  # Hello, Alice!

# 带默认参数的函数
def introduce(name, age=18):
    return f"My name is {name}, I'm {age} years old."

print(introduce("Bob"))        # My name is Bob, I'm 18 years old.
print(introduce("Charlie", 25)) # My name is Charlie, I'm 25 years old.

# 返回多个值
def calculate(a, b):
    return a + b, a - b, a * b

sum_result, diff_result, product_result = calculate(10, 5)

Lambda 函数

# 匿名函数
square = lambda x: x ** 2
print(square(5))  # 25

# 在排序中使用
students = [("Alice", 20), ("Bob", 18), ("Charlie", 22)]
students.sort(key=lambda student: student[1])
print(students)  # [('Bob', 18), ('Alice', 20), ('Charlie', 22)]

五、文件操作

# 写入文件
with open("example.txt", "w", encoding="utf-8") as file:
    file.write("Hello, World!\n")
    file.write("This is a text file.\n")

# 读取文件
with open("example.txt", "r", encoding="utf-8") as file:
    content = file.read()
    print(content)

# 逐行读取
with open("example.txt", "r", encoding="utf-8") as file:
    for line in file:
        print(line.strip())

六、异常处理

try:
    num = int(input("请输入一个数字: "))
    result = 10 / num
    print(f"结果是: {result}")
except ValueError:
    print("输入错误，请输入有效的数字！")
except ZeroDivisionError:
    print("错误：不能除以零！")
except Exception as e:
    print(f"发生未知错误: {e}")
else:
    print("计算成功完成！")
finally:
    print("程序执行完毕。")

七、面向对象编程

类与对象

class Student:
    # 类属性
    school = "ABC School"
    
    # 初始化方法
    def __init__(self, name, age):
        self.name = name  # 实例属性
        self.age = age
    
    # 实例方法
    def introduce(self):
        return f"My name is {self.name}, I'm {self.age} years old."
    
    # 类方法
    @classmethod
    def get_school_info(cls):
        return f"This is {cls.school}"

# 创建对象
student1 = Student("Alice", 20)
print(student1.introduce())  # My name is Alice, I'm 20 years old.
print(Student.get_school_info())  # This is ABC School

继承

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
    
    def speak(self):
        return f"My name is {self.name}"

class Teacher(Person):
    def __init__(self, name, age, subject):
        super().__init__(name, age)
        self.subject = subject
    
    def speak(self):
        return f"I'm {self.name}, I teach {self.subject}"

teacher = Teacher("Mr. Smith", 35, "Math")
print(teacher.speak())  # I'm Mr. Smith, I teach Math

八、模块与包

# 导入整个模块
import math
print(math.sqrt(16))  # 4.0

# 导入特定函数
from math import pi, cos
print(pi)  # 3.141592653589793

# 给模块起别名
import numpy as np
import pandas as pd

九、列表推导式

# 基本列表推导式
squares = [x**2 for x in range(1, 6)]
print(squares)  # [1, 4, 9, 16, 25]

# 带条件的列表推导式
even_squares = [x**2 for x in range(1, 11) if x % 2 == 0]
print(even_squares)  # [4, 16, 36, 64, 100]

# 字典推导式
square_dict = {x: x**2 for x in range(1, 6)}
print(square_dict)  # {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}

十、常用内置函数

# len() - 获取长度
print(len("hello"))  # 5
print(len([1, 2, 3]))  # 3

# range() - 生成数字序列
print(list(range(5)))  # [0, 1, 2, 3, 4]

# enumerate() - 同时获取索引和值
fruits = ["apple", "banana", "orange"]
for index, fruit in enumerate(fruits):
    print(f"{index}: {fruit}")

# zip() - 合并多个序列
names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]
for name, age in zip(names, ages):
    print(f"{name} is {age} years old")

这些基础知识点是学习 python 的基石，掌握它们将为学习AI和训练AI大模型提供基础。

建议通过实际写代码来巩固这些知识。