# 创建列表
fruits = ["apple", "banana", "cherry"]
numbers = [1, 3, 5, 7, 9]
mixed = [1, "hello", True, 3.14]
nested = [["a", "b"], [1, 2, 3]]

# 访问列表元素
print(fruits[0])  # 输出: apple
print(numbers[2])  # 输出: 5
print(mixed[-1])  # 输出: 3.14 (负数索引从末尾开始)
print(nested[1][0])  # 输出: 1 (访问嵌套列表)

# 修改列表元素
fruits[1] = "grape"
print(fruits)  # 输出: ['apple', 'grape', 'cherry']

# 列表长度
fruits = ["apple", "banana", "cherry", "date"]
print(len(fruits))  # 输出: 4

# 列表切片
print(fruits[1:3])  # 输出: ['banana', 'cherry'] (索引1到2)
print(fruits[:2])   # 输出: ['apple', 'banana'] (从开始到索引1)
print(fruits[2:])   # 输出: ['cherry', 'date'] (从索引2到结束)
print(fruits[-2:])  # 输出: ['cherry', 'date'] (最后两个元素)
print(fruits[::2])  # 输出: ['apple', 'cherry'] (每隔一个元素)
print(fruits[::-1]) # 输出: ['date', 'cherry', 'banana', 'apple'] (反转列表)

# append() - 在列表末尾添加元素
fruits = ["apple", "banana"]
fruits.append("cherry")
print(fruits)  # 输出: ['apple', 'banana', 'cherry']

# extend() - 在列表末尾添加多个元素
fruits.extend(["date", "elderberry"])
print(fruits)  # 输出: ['apple', 'banana', 'cherry', 'date', 'elderberry']

# insert() - 在指定位置插入元素
fruits.insert(1, "blueberry")
print(fruits)  # 输出: ['apple', 'blueberry', 'banana', 'cherry', 'date', 'elderberry']

# 使用 + 运算符连接列表
vegetables = ["carrot", "potato"]
produce = fruits + vegetables
print(produce)  # 输出: ['apple', 'blueberry', 'banana', 'cherry', 'date', 'elderberry', 'carrot', 'potato']

# remove() - 删除指定值的第一个匹配项
fruits = ["apple", "banana", "cherry", "banana"]
fruits.remove("banana")
print(fruits)  # 输出: ['apple', 'cherry', 'banana']

# pop() - 删除并返回指定位置的元素
removed = fruits.pop(1)
print(removed)  # 输出: cherry
print(fruits)   # 输出: ['apple', 'banana']

# del - 删除指定位置的元素
del fruits[0]
print(fruits)  # 输出: ['banana']

# clear() - 清空列表
fruits.clear()
print(fruits)  # 输出: []

# 修改单个元素
numbers = [1, 2, 3, 4, 5]
numbers[2] = 10
print(numbers)  # 输出: [1, 2, 10, 4, 5]

# 替换多个元素
numbers[1:3] = [20, 30]
print(numbers)  # 输出: [1, 20, 30, 4, 5]

# 用切片删除元素
numbers[1:3] = []
print(numbers)  # 输出: [1, 4, 5]

# 用切片插入元素
numbers[1:1] = [2, 3]
print(numbers)  # 输出: [1, 2, 3, 4, 5]

# count() - 统计元素出现次数
numbers = [1, 2, 3, 2, 4, 2]
print(numbers.count(2))  # 输出: 3

# index() - 返回元素第一次出现的索引
print(numbers.index(2))  # 输出: 1
print(numbers.index(2, 2))  # 输出: 3 (从索引2开始查找)

# sort() - 对列表进行排序
numbers.sort()
print(numbers)  # 输出: [1, 2, 2, 2, 3, 4]

# reverse() - 反转列表
numbers.reverse()
print(numbers)  # 输出: [4, 3, 2, 2, 2, 1]

# copy() - 复制列表
new_numbers = numbers.copy()
print(new_numbers)  # 输出: [4, 3, 2, 2, 2, 1]

# 使用 sort() 的 key 参数
words = ["apple", "Banana", "cherry", "Date"]
words.sort()  # 默认按ASCII码排序
print(words)  # 输出: ['Banana', 'Date', 'apple', 'cherry']

# 忽略大小写排序
words.sort(key=str.lower)
print(words)  # 输出: ['apple', 'Banana', 'cherry', 'Date']

# 自定义排序函数
numbers = [1, 5, 2, 10, 3]
numbers.sort(key=lambda x: x % 2)  # 按奇偶性排序
print(numbers)  # 输出: [2, 10, 1, 5, 3]

# 使用 sorted() 函数返回新列表
original = [3, 1, 4, 1, 5, 9]
sorted_list = sorted(original)
print(sorted_list)  # 输出: [1, 1, 3, 4, 5, 9]
print(original)     # 输出: [3, 1, 4, 1, 5, 9] (原始列表不变)

# 使用 for 循环遍历列表
fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
  print(fruit)  # 依次输出: apple, banana, cherry

# 使用索引遍历列表
for i in range(len(fruits)):
  print(fruits[i])  # 依次输出: apple, banana, cherry

# 使用 enumerate() 获取索引和值
for index, fruit in enumerate(fruits):
  print(f"Index {index}: {fruit}")  # 依次输出: Index 0: apple, Index 1: banana, Index 2: cherry

# 使用 while 循环遍历列表
i = 0
while i < len(fruits):
  print(fruits[i])
  i += 1  # 依次输出: apple, banana, cherry

# 基本列表推导式
squares = [x**2 for x in range(5)]
print(squares)  # 输出: [0, 1, 4, 9, 16]

# 带条件的列表推导式
even_numbers = [x for x in range(10) if x % 2 == 0]
print(even_numbers)  # 输出: [0, 2, 4, 6, 8]

# 嵌套列表推导式
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
flattened = [element for row in matrix for element in row]
print(flattened)  # 输出: [1, 2, 3, 4, 5, 6, 7, 8, 9]

# 条件表达式在列表推导式中
numbers = [1, 2, 3, 4, 5]
result = ["偶数" if x % 2 == 0 else "奇数" for x in numbers]
print(result)  # 输出: ['奇数', '偶数', '奇数', '偶数', '奇数']

# 合并列表
list1 = [1, 2, 3]
list2 = [4, 5, 6]

# 使用 + 运算符
combined = list1 + list2
print(combined)  # 输出: [1, 2, 3, 4, 5, 6]

# 使用 extend() 方法
list1.extend(list2)
print(list1)  # 输出: [1, 2, 3, 4, 5, 6]

# 使用 * 运算符复制列表
duplicated = list1 * 2
print(duplicated)  # 输出: [1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 5, 6]

# 拆分列表
numbers = [1, 2, 3, 4, 5, 6]
first_half = numbers[:len(numbers)//2]
second_half = numbers[len(numbers)//2:]
print(first_half)  # 输出: [1, 2, 3]
print(second_half)  # 输出: [4, 5, 6]

# 反转列表
numbers = [1, 2, 3, 4, 5]

# 使用 reverse() 方法
numbers.reverse()
print(numbers)  # 输出: [5, 4, 3, 2, 1]

# 使用切片反转
numbers = [1, 2, 3, 4, 5]
reversed_numbers = numbers[::-1]
print(reversed_numbers)  # 输出: [5, 4, 3, 2, 1]

# 排序列表
words = ["banana", "apple", "cherry"]

# 使用 sort() 方法
words.sort()
print(words)  # 输出: ['apple', 'banana', 'cherry']

# 使用 sorted() 函数
words = ["banana", "apple", "cherry"]
sorted_words = sorted(words)
print(sorted_words)  # 输出: ['apple', 'banana', 'cherry']
print(words)  # 输出: ['banana', 'apple', 'cherry'] (原始列表不变)

# 创建二维列表
matrix = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9]
]

# 访问二维列表
print(matrix[1][2])  # 输出: 6 (第二行第三列)

# 修改二维列表
matrix[0][0] = 10
print(matrix)  # 输出: [[10, 2, 3], [4, 5, 6], [7, 8, 9]]

# 遍历二维列表
for row in matrix:
  for element in row:
      print(element, end=" ")
  print()  # 换行，输出: 10 2 3 4 5 6 7 8 9

# 创建多维列表
cube = [
  [[1, 2], [3, 4]],
  [[5, 6], [7, 8]]
]
print(cube[1][0][1])  # 输出: 6

# 传递列表给函数
def sum_list(numbers):
  total = 0
  for num in numbers:
      total += num
  return total

numbers = [1, 2, 3, 4, 5]
print(sum_list(numbers))  # 输出: 15

# 从函数返回列表
def generate_squares(n):
  return [x**2 for x in range(1, n+1)]

squares = generate_squares(5)
print(squares)  # 输出: [1, 4, 9, 16, 25]

# 修改列表的函数
def double_list(numbers):
  for i in range(len(numbers)):
      numbers[i] *= 2
  return numbers

numbers = [1, 2, 3]
doubled = double_list(numbers)
print(doubled)  # 输出: [2, 4, 6]
print(numbers)  # 输出: [2, 4, 6] (原始列表被修改)