Topics

Tuple

Tuple Creation

Tuple is very similar to a list, which contains a sequence of objects. Its main difference is it cannot be modified after creation. A tuple is created by assigning a list of comma-separated values to a variable. For clarity, it is recommended to enclose the values with the parentheses.


# create a tuple with values: 'a', 'b', 'c'
>>> t1 = ('a', 'b', 'c')                
>>> type(t1)


# create a tuple with values: 1, 2, 3, 4, 5
>>> t2 = 1, 2, 3, 4, 5                  
>>> t2
(1, 2, 3, 4, 5)

# create an empty tuple
>>> t3 = ()                             

# create a tuple with one element, 
# need to add a comma 
>>> t4 = (5,)

Accessing Values in a Tuple

Like List and String, Tuple is zero indexed. The same slicing rule applies for accessing elements within a tuple. See examples below:


>>> x = ('a', 'b', 'c', 'd', 'e')

# Getting first element
>>> x[0]                                
'a'

# Getting last element
>>> x[-1]                               
'e'

# Getting second and third elements using slicing
>>> x[1:3]                              
('b', 'c')

Modifying a Tuple

Tuple is immutable, and therefore its value cannot be modified directly. However, you can “modify” a tuple by re-assigning the value to another tuple.


>>> a = (1, 2, 3, 4, 5)
>>> a[0] = 10
Traceback (most recent call last):
  File "<interactive input>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

# replace the first element with (10,), 
# and reassign the result to a new tuple
>>> b = (10,) + a[1:]       
>>> b
(10, 2, 3, 4, 5)

# Not allowed to delete elements in a tuple
>>> del a[0]                
Traceback (most recent call last):
  File "<interactive input>", line 1, in <module>
TypeError: 'tuple' object does not support item deletion

# You can delete the whole tuple
>>> del a

Other useful tuple operations

Those list functions that does not modify the content of the list can also be used with Tuple.


>>> x = (2, 6, 3, 1, 10, 5)

# get number of items in the tuple
>>> len(x)                      
6

# get the maximum value in the tuple
>>> max(x)                      
10

# get the minimum value in the tuple
>>> min(x)                      
1

# get the number of 5 in the tuple
>>> x.count(5)                  
1