Python中的元组

元组是由逗号分隔的Python对象的集合。在某些方面，元组在索引、嵌套对象和重复方面类似于列表，但元组是不可变的，不像列表是可变的。

创建元组

# An empty tuple
empty_tuple = ()
print (empty_tuple)

输出：

()

# Creating non-empty tuples
 
# One way of creation
tup = 'python', 'geeks'
print(tup)
 
# Another for doing the same
tup = ('python', 'geeks')
print(tup)

输出

('python', 'geeks')
('python', 'geeks')

注意：如果您使用单个元素生成元组，请确保在元素后添加逗号。

元组的连接

# Code for concatenating 2 tuples
 
tuple1 = (0, 1, 2, 3)
tuple2 = ('python', 'geek')
 
# Concatenating above two
print(tuple1 + tuple2)

输出：

(0, 1, 2, 3, 'python', 'geek')

元组的嵌套

# Code for creating nested tuples
 
tuple1 = (0, 1, 2, 3)
tuple2 = ('python', 'geek')
tuple3 = (tuple1, tuple2)
print(tuple3)

输出 ：

((0, 1, 2, 3), ('python', 'geek'))

元组中的重复

# Code to create a tuple with repetition
 
tuple3 = ('python',)*3
print(tuple3)

输出

('python', 'python', 'python')

试试上面没有逗号并检查。您将得到 tuple3 作为字符串'pythonpythonpython'。

不可变元组

#code to test that tuples are immutable
 
tuple1 = (0, 1, 2, 3)
tuple1[0] = 4
print(tuple1)

输出

Traceback (most recent call last):
  File "e0eaddff843a8695575daec34506f126.py", line 3, in
    tuple1[0]=4
TypeError: 'tuple' object does not support item assignment

在元组中切片

# code to test slicing
 
tuple1 = (0 ,1, 2, 3)
print(tuple1[1:])
print(tuple1[::-1])
print(tuple1[2:4])

输出

(1, 2, 3)
(3, 2, 1, 0)
(2, 3)

删除元组

# Code for deleting a tuple
 
tuple3 = ( 0, 1)
del tuple3
print(tuple3)

错误：

Traceback (most recent call last):
  File "d92694727db1dc9118a5250bf04dafbd.py", line 6, in 
    print(tuple3)
NameError: name 'tuple3' is not defined

输出：

(0, 1)

查找元组的长度

# Code for printing the length of a tuple
 
tuple2 = ('python', 'geek')
print(len(tuple2))

输出

2

将列表转换为元组

# Code for converting a list and a string into a tuple
 
list1 = [0, 1, 2]
print(tuple(list1))
print(tuple('python')) # string 'python'

输出

(0, 1, 2)
('p', 'y', 't', 'h', 'o', 'n')

接受一个参数，它可以是一个列表、字符串、集合甚至是一个字典（只有键被视为元素）并将它们转换为元组。

循环中的元组

#python code for creating tuples in a loop
 
tup = ('geek',)
n = 5  #Number of time loop runs
for i in range(int(n)):
    tup = (tup,)
    print(tup)

输出 ：

(('geek',),)
((('geek',),),)
(((('geek',),),),)
((((('geek',),),),),)
(((((('geek',),),),),),)

使用 cmp()、max()、min()

# A python program to demonstrate the use of
# cmp(), max(), min()
 
tuple1 = ('python', 'geek')
tuple2 = ('coder', 1)
 
if (cmp(tuple1, tuple2) != 0):
 
    # cmp() returns 0 if matched, 1 when not tuple1
    # is longer and -1 when tuple1 is shorter
    print('Not the same')
else:
    print('Same')
print ('Maximum element in tuples 1,2: ' +
        str(max(tuple1)) +  ',' +
        str(max(tuple2)))
print ('Minimum element in tuples 1,2: ' +
     str(min(tuple1)) + ','  + str(min(tuple2)))

输出

Not the same
Maximum element in tuples 1,2: python,coder
Minimum element in tuples 1,2: geek,1

注意：max() 和 min() 检查基于 ASCII 值。如果元组中有两个字符串，则检查字符串中的第一个不同字符。