python中的元组类型

1、元组的特点

• 元组的关键字：tuple

• 定义符号：()

• 元组中的内容不可修改

• 如果元组中只有一个元素，该元素后需要跟一个逗号，否则()不起作用

  t1 = ()
  print(type(t1))			# <class 'tuple'>
  
  t2 = (10)
  print(type(t2))			# <class 'int'>
  
  t3 = (10,)
  print(type(t3))			# <class 'tuple'>
  

2、元组元素的放入

​ 元组不能被修改，即不能增加、修改、删除元组中的元素，但可以通过tuple()来将列表转换成元组类型

import random

# 生成10个随机数的列表
ran_list = []
i = 1
while i <= 10:
    ran = random.randint(1, 20)
    if ran not in ran_list:
        ran_list.append(ran)
        i += 1
print(ran_list)

t = tuple(ran_list)
print(t)

3、元组的查询

t = (19, 3, 7, 4, 18, 6, 13, 17, 14, 12)

print(t[3])			# 4
print(t[3:-3])		# (4, 18, 6, 13)
print(t[::-1])		# (12, 14, 17, 13, 6, 18, 4, 7, 3, 19)
print(max(t))		# 19
print(min(t))		# 3
print(sum(t))		# 113
print(len(t))		# 10

4、元组中的函数

• t.count(value)：返回元组t中value出现的次数

  t = (19, 3, 7, 4, 18, 3, 13, 17, 14, 12)
  
  print(t.count(3))	# 2
  

• t.index(value)：返回元组t中value第一次出现的下标

  t = (19, 3, 7, 4, 18, 3, 13, 17, 14, 12)
  
  print(t.index(3))		# 1
  print(t.index(5))		# ValueError: tuple.index(x): x not in tuple
  

5、元组的拆包和装包

t = (5, 8, 1)

a, b = t
print(a, b)				# ValueError: too many values to unpack (expected 2)

w, x, y, z = t
print(w, x, y, z)		# ValueError: not enough values to unpack (expected 4, got 3)

x, y, z = t
print(x, y, z)			# 5 8 1

t1 = (1, 5, 2, 9)
a, *b, c = t1
print(a, c, b)			# 1 9 [5, 2]

t2 = (1,)
a, *b = t2
print(a, b)				# 1 []