python# 空列表empty_list = []empty_list2 = list()# 包含元素的列表numbers = [1, 2, 3, 4, 5]fruits = ['apple', 'banana', 'orange']mixed = [1, 'hello', 3.14, True]# 多维列表（列表的列表）matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

pythonfruits = ['apple', 'banana', 'orange', 'grape']# 通过索引访问（从0开始）print(fruits[0])  # 输出: appleprint(fruits[2])  # 输出: orange# 负索引表示从末尾开始print(fruits[-1])  # 输出: grapeprint(fruits[-2])  # 输出: orange# 切片操作 [start:end:step]print(fruits[1:3])    # 输出: ['banana', 'orange']print(fruits[:2])     # 输出: ['apple', 'banana']print(fruits[2:])     # 输出: ['orange', 'grape']print(fruits[::2])    # 输出: ['apple', 'orange']print(fruits[::-1])   # 输出: ['grape', 'orange', 'banana', 'apple'] (反转列表)

pythonnumbers = [1, 2, 3, 4, 5]# 修改单个元素numbers[1] = 20print(numbers)  # [1, 20, 3, 4, 5]# 修改多个元素（切片赋值）numbers[1:4] = [22, 33, 44]print(numbers)  # [1, 22, 33, 44, 5]# 替换的元素数量可以不同numbers[1:4] = [99, 88]print(numbers)  # [1, 99, 88, 5]

pythonfruits = ['apple', 'banana']# append() - 在末尾添加单个元素fruits.append('orange')print(fruits)  # ['apple', 'banana', 'orange']# insert() - 在指定位置插入元素fruits.insert(1, 'grape')print(fruits)  # ['apple', 'grape', 'banana', 'orange']# extend() - 合并列表（相当于 +=）more_fruits = ['pear', 'peach']fruits.extend(more_fruits)print(fruits)  # ['apple', 'grape', 'banana', 'orange', 'pear', 'peach']# + 运算符也可以合并列表new_fruits = fruits + ['melon', 'kiwi']print(new_fruits)

pythonnumbers = [1, 2, 3, 4, 5]# del 语句 - 按索引删除del numbers[1]print(numbers)  # [1, 3, 4, 5]# pop() - 删除并返回指定位置的元素（默认最后一个）removed = numbers.pop()print(removed)  # 5print(numbers)  # [1, 3, 4]removed = numbers.pop(0)print(removed)  # 1print(numbers)  # [3, 4]# remove() - 按值删除（删除第一个匹配项）letters = ['a', 'b', 'c', 'a']letters.remove('a')print(letters)  # ['b', 'c', 'a']# clear() - 清空列表letters.clear()print(letters)  # []

pythonnums = [3, 1, 4, 1, 5, 9, 2]# count() - 统计元素出现次数print(nums.count(1))  # 2# index() - 返回元素第一次出现的索引print(nums.index(5))  # 4# reverse() - 反转列表（原地修改）nums.reverse()print(nums)  # [2, 9, 5, 1, 4, 1, 3]# sort() - 排序（原地修改）nums.sort()print(nums)  # [1, 1, 2, 3, 4, 5, 9]# sorted() - 返回排序后的新列表（不修改原列表）nums = [3, 1, 4, 1, 5, 9, 2]sorted_nums = sorted(nums)print(nums)      # [3, 1, 4, 1, 5, 9, 2] (未修改)print(sorted_nums)  # [1, 1, 2, 3, 4, 5, 9]

python# 自定义排序students = [{'name': 'Alice', 'score': 85},{'name': 'Bob', 'score': 92},{'name': 'Charlie', 'score': 78}]# 按分数升序排序students.sort(key=lambda x: x['score'])print(students)# 按分数降序排序students.sort(key=lambda x: x['score'], reverse=True)print(students)# 使用 cmp 参数（Python3 中需要 functools.cmp_to_key）from functools import cmp_to_keydef compare(a, b):if a['score'] < b['score']:return -1elif a['score'] > b['score']:return 1else:return 0students.sort(key=cmp_to_key(compare))print(students)

python# 创建0-9的平方列表squares = [x**2 for x in range(10)]print(squares)  # [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]# 带条件的列表推导式even_squares = [x**2 for x in range(10) if x % 2 == 0]print(even_squares)  # [0, 4, 16, 36, 64]

python# 创建乘法表matrix = [[i*j for j in range(1, 6)] for i in range(1, 6)]for row in matrix:print(row)# 输出:# [1, 2, 3, 4, 5]# [2, 4, 6, 8, 10]# [3, 6, 9, 12, 15]# [4, 8, 12, 16, 20]# [5, 10, 15, 20, 25]# 展平二维列表flat = [num for row in matrix for num in row]print(flat)  # [1, 2, 3, 4, 5, 2, 4, 6, 8, 10, ...]

pythonoriginal = [1, 2, [3, 4]]# 浅拷贝（shallow copy）shallow_copy = original.copy()  # 或 original[:] 或 list(original)shallow_copy[0] = 10shallow_copy[2][0] = 30print(original)  # [1, 2, [30, 4]] (嵌套列表被修改)# 深拷贝（deep copy）import copydeep_copy = copy.deepcopy(original)deep_copy[2][0] = 300print(original)  # [1, 2, [30, 4]] (不受影响)

python# enumerate() - 获取索引和值fruits = ['apple', 'banana', 'orange']for index, fruit in enumerate(fruits):print(f"{index}: {fruit}")# zip() - 合并多个列表names = ['Alice', 'Bob', 'Charlie']ages = [25, 30, 35]for name, age in zip(names, ages):print(f"{name} is {age} years old")# filter() - 过滤列表numbers = [1, 2, 3, 4, 5, 6]even_numbers = list(filter(lambda x: x % 2 == 0, numbers))print(even_numbers)  # [2, 4, 6]# map() - 应用函数到每个元素squared = list(map(lambda x: x**2, numbers))print(squared)  # [1, 4, 9, 16, 25, 36]

python# 解包列表first, *middle, last = [1, 2, 3, 4, 5]print(first)  # 1print(middle)  # [2, 3, 4]print(last)   # 5# 交换变量a, b = 1, 2a, b = b, aprint(a, b)  # 2 1# 合并列表list1 = [1, 2, 3]list2 = ['a', 'b', 'c']combined = [*list1, *list2]print(combined)  # [1, 2, 3, 'a', 'b', 'c']

python# 计算学生平均分students = [{'name': 'Alice', 'scores': [85, 90, 78]},{'name': 'Bob', 'scores': [92, 88, 91]},{'name': 'Charlie', 'scores': [78, 82, 85]}]# 计算每个学生的平均分for student in students:avg = sum(student['scores']) / len(student['scores'])student['average'] = avgprint(students)# 输出:# [#     {'name': 'Alice', 'scores': [85, 90, 78], 'average': 84.333...},#     {'name': 'Bob', 'scores': [92, 88, 91], 'average': 90.333...},#     {'name': 'Charlie', 'scores': [78, 82, 85], 'average': 81.666...}# ]

python# 矩阵转置matrix = [[1, 2, 3],[4, 5, 6],[7, 8, 9]]transposed = [[row[i] for row in matrix] for i in range(3)]print(transposed)# 输出:# [[1, 4, 7], [2, 5, 8], [3, 6, 9]]# 或者使用 zip()transposed_zip = list(zip(*matrix))print(transposed_zip)  # [(1, 4, 7), (2, 5, 8), (3, 6, 9)] (元组形式)

pythondef flatten(nested_list):flat_list = []for item in nested_list:if isinstance(item, list):flat_list.extend(flatten(item))else:flat_list.append(item)return flat_listnested = [1, [2, [3, 4], 5], 6]print(flatten(nested))  # [1, 2, 3, 4, 5, 6]