Tuple

创建元组

# 创建空元组
empty_tuple = ()
# or using the tuple constructor
empty_tuple = tuple()

# 具有初始值的元组
tpl = ('item1', 'item2','item3')
fruits = ('banana', 'orange', 'mango', 'lemon')

元组长度

#  len()方法来获取元组的长度
tpl = ('item1', 'item2', 'item3')
len(tpl)

检查元组中的项

# 使用 in 检查元组中是否存在一个项目，它返回一个布尔值
tpl = ('item1', 'item2', 'item3','item4')
'item2' in tpl # True

fruits = ('banana', 'orange', 'mango', 'lemon')
print('orange' in fruits) # True
print('apple' in fruits) # False
fruits[0] = 'apple' # TypeError: 'tuple' object does not support item assignment

访问元组中的项

# 正索引
tpl = ('item1', 'item2', 'item3')
first_item = tpl[0]
second_item = tpl[1]

fruits = ('banana', 'orange', 'mango', 'lemon')
first_fruit = fruits[0]
second_fruit = fruits[1]
last_index =len(fruits) - 1
last_fruit = fruits[las_index]

# 负索引
tpl = ('item1', 'item2', 'item3','item4')
first_item = tpl[-4]
second_item = tpl[-3]

fruits = ('banana', 'orange', 'mango', 'lemon')
first_fruit = fruits[-4]
second_fruit = fruits[-3]
last_fruit = fruits[-1]

元组切片

# 正指数范围
tpl = ('item1', 'item2', 'item3','item4')
all_items = tpl[0:4]         # all items
all_items = tpl[0:]         # all items
middle_two_items = tpl[1:3]  # does not include item at index 3

# 负指数范围
tpl = ('item1', 'item2', 'item3','item4')
all_items = tpl[-4:]         # all items
middle_two_items = tpl[-3:-1]  # does not include item at index 3 (-1)

fruits = ('banana', 'orange', 'mango', 'lemon')
all_fruits = fruits[-4:]    # all items
orange_mango = fruits[-3:-1]  # doesn't include item at index 3
orange_to_the_rest = fruits[-3:]

将元组更改为列表

# 将元组更改为列表，将列表更改为元组
# 元组是不可变的，如果我们想修改元组，我们应该将其更改为列表
tpl = ('item1', 'item2', 'item3','item4')
lst = list(tpl)

fruits = ('banana', 'orange', 'mango', 'lemon')
fruits = list(fruits)
fruits[0] = 'apple'
print(fruits)     # ['apple', 'orange', 'mango', 'lemon']
fruits = tuple(fruits)
print(fruits)     # ('apple', 'orange', 'mango', 'lemon')

连接元组

# 使用 + 运算符连接两个或多个元组
tpl1 = ('item1', 'item2', 'item3')
tpl2 = ('item4', 'item5','item6')
tpl3 = tpl1 + tpl2

fruits = ('banana', 'orange', 'mango', 'lemon')
vegetables = ('Tomato', 'Potato', 'Cabbage','Onion', 'Carrot')
fruits_and_vegetables = fruits + vegetables

删除元组

# 无法删除元组中的单个项目，但可以使用 del 删除元组本身
tpl1 = ('item1', 'item2', 'item3')
del tpl1

fruits = ('banana', 'orange', 'mango', 'lemon')
del fruits