Introduction to Tuples

A tuple is an ordered sequence of elements of different data types, such as integer, float, string, list or even a tuple. Elements of a tuple are enclosed in parenthesis (round brackets) and are separated by commas. Like list and string, elements of a tuple can be accessed using index values, starting from 0.

Example

#tuple1 is the tuple of integers
>>> tuple1 = (1,2,3,4,5)
>>> tuple1
(1, 2, 3, 4, 5)
#tuple2 is the tuple of mixed data types
>>> tuple2 =('Economics',87,'Accountancy',89.6)
>>> tuple2
('Economics', 87, 'Accountancy', 89.6)
#tuple3 is the tuple with list as an element
>>> tuple3 = (10,20,30,[40,50])
>>> tuple3
(10, 20, 30, [40, 50])
#tuple4 is the tuple with tuple as an element
>>> tuple4 = (1,2,3,4,5,(10,20))
>>> tuple4
(1, 2, 3, 4, 5, (10, 20))

If there is only a single element in a tuple then the element should be followed by a comma. If we assign the value without comma it is treated as integer. It should be noted that a sequence without parenthesis is treated as tuple by default.

Example

#incorrect way of assigning single element to
#tuple
#tuple5 is assigned a single element
>>> tuple5 = (20)
>>> tuple5
20
>>>type(tuple5) #tuple5 is not of type tuple
<class 'int'> #it is treated as integer

#Correct Way of assigning single element to
#tuple
#tuple5 is assigned a single element
>>> tuple5 = (20,) #element followed by comma
>>> tuple5
(20,)
>>>type(tuple5) #tuple5 is of type tuple
<class 'tuple'<

#a sequence without parentheses is treated as
#tuple by default
>>> seq = 1,2,3 #comma separated elements
>>> type(seq) #treated as tuple
<class 'tuple'<
>>> print(seq) #seq is a tuple
(1, 2, 3) 

Accessing Elements in a Tuple

Elements of a tuple can be accessed in the same way as a list or string using indexing and slicing.

>>> tuple1 = (2,4,6,8,10,12)
#initializes a tuple tuple1
#returns the first element of tuple1
>>> tuple1[0]
2
#returns fourth element of tuple1
>>> tuple1[3]
8
#returns error as index is out of range
>>> tuple1[15]
IndexError: tuple index out of range
#an expression resulting in an integer index
>>> tuple1[1+4]
12
#returns first element from right
>>> tuple1[-1]
12

Tuple is Immutable

Tuple is an immutable data type. It means that the elements of a tuple cannot be changed after it has been created. An attempt to do this would lead to an error.

>>> tuple1 = (1,2,3,4,5)
>>> tuple1[4] = 10
TypeError: 'tuple' object does not support
item assignment

However an element of a tuple may be of mutable type, e.g., a list.

#4th element of the tuple2 is a list
>>> tuple2 = (1,2,3,[8,9])
#modify the list element of the tuple tuple2
>>> tuple2[3][1] = 10
#modification is reflected in tuple2
>>> tuple2
(1, 2, 3, [8, 10])

Tuple Operations

Concatenation

Python allows us to join tuples using concatenation operator depicted by symbol +. We can also create a new tuple which contains the result of this concatenation operation.

>>> tuple1 = (1,3,5,7,9)
>>> tuple2 = (2,4,6,8,10)
>>> tuple1 + tuple2
#concatenates two tuples
(1, 3, 5, 7, 9, 2, 4, 6, 8, 10)

>>> tuple3 = ('Red','Green','Blue')
>>> tuple4 = ('Cyan', 'Magenta', 'Yellow','Black')
#tuple5 stores elements of tuple3 and tuple4
>>> tuple5 = tuple3 + tuple4
>>> tuple5
('Red','Green','Blue','Cyan','Magenta','Yellow','Black')

Concatenation operator can also be used for extending an existing tuple. When we extend a tuple using concatenation a new tuple is created.

>>> tuple6 = (1,2,3,4,5)
#single element is appended to tuple6
>>> tuple6 = tuple6 + (6,)
>>> tuple6
(1, 2, 3, 4, 5, 6)

#more than one elements are appended
>>> tuple6 = tuple6 + (7,8,9)
>>> tuple6
(1, 2, 3, 4, 5, 6, 7, 8, 9)

Repetition

Repetition operation is depicted by the symbol *. It is used to repeat elements of a tuple. We can repeat the tuple elements. The repetition operator requires the first operand to be a tuple and the second operand to be an integer only.

>>> tuple1 = ('Hello','World')
>>> tuple1 * 3
('Hello', 'World', 'Hello', 'World', 'Hello',
'World')
#tuple with single element
>>> tuple2 = ("Hello",)
>>> tuple2 * 4
('Hello', 'Hello', 'Hello', 'Hello')

Membership

The in operator checks if the element is present in the tuple and returns True, else it returns False.

>>> tuple1 = ('Red','Green','Blue')
>>> 'Green' in tuple1
True

The not in operator returns True if the element is not present in the tuple, else it returns False.

>>> tuple1 = ('Red','Green','Blue')
>>> 'Green' not in tuple1
False

Slicing

Like string and list, slicing can be applied to tuples also.

#tuple1 is a tuple
>>> tuple1 = (10,20,30,40,50,60,70,80)
#elements from index 2 to index 6
>>> tuple1[2:7]
(30, 40, 50, 60, 70)
#all elements of tuple are printed
>>> tuple1[0:len(tuple1)]
(10, 20, 30, 40, 50, 60, 70, 80)
#slice starts from zero index
>>> tuple1[:5]
(10, 20, 30, 40, 50)
#slice is till end of the tuple
>>> tuple1[2:]
(30, 40, 50, 60, 70, 80)
#step size 2
>>> tuple1[0:len(tuple1):2]
(10, 30, 50, 70)
#negative indexing
>>> tuple1[-6:-4]
(30, 40)
#tuple is traversed in reverse order
>>> tuple1[::-1]
(80, 70, 60, 50, 40, 30, 20, 10)

Tuple Methods and Built-in Functions

Python provides many functions to work on tuples. The following list some of the commonly used tuple methods and built-in functions.

>>> tuple1 = (10,20,30,40,50)
>>> len(tuple1)
5

>>> tuple1 = tuple()
>>> tuple1
( )
>>> tuple1 = tuple('aeiou')#string
>>> tuple1
('a', 'e', 'i', 'o', 'u')
>>> tuple2 = tuple([1,2,3]) #list
>>> tuple2
(1, 2, 3)
>>> tuple3 = tuple(range(5))
>>> tuple3
(0, 1, 2, 3, 4)

>>> tuple1 = (10,20,30,10,40,10,50)
>>> tuple1.count(10)
3>
>> tuple1.count(90)
0

>>> tuple1 = (10,20,30,40,50)
>>> tuple1.index(30)
2>
>> tuple1.index(90)
ValueError: tuple.index(x): x not
in tuple

>>> tuple1 = ("Rama","Heena","Raj",
"Mohsin","Aditya")
>>> sorted(tuple1)
['Aditya', 'Heena', 'Mohsin', 'Raj','Rama']

>>> tuple1 = (19,12,56,18,9,87,34)
>>> min(tuple1)
9

>>> tuple1 = (19,12,56,18,9,87,34)
>>> max(tuple1)
87

>>> tuple1 = (19,12,56,18,9,87,34)
>>> sum(tuple1)
235

Tuple Assignment

Assignment of tuple is a useful feature in Python. It allows a tuple of variables on the left side of the assignment operator to be assigned respective values from a tuple on the right side. The number of variables on the left should be same as the number of elements in the tuple.

Example

#The first element 10 is assigned to num1 and
#the second element 20 is assigned to num2.
>>> (num1,num2) = (10,20)
>>> print(num1)
10
>>> print(num2)
20
>>> record = ( "Pooja",40,"CS")
>>> (name,rollNo,subject) = record
>>> name
'Pooja'
>>> rollNo
40
>>> subject
'CS'
>>> (a,b,c,d) = (5,6,8)
ValueError: not enough values to unpack
(expected 4, got 3)

If there is an expression on the right side then first that expression is evaluated and finally the result is assigned to the tuple.

Example

#15 is assigned to num3 and
#25 is assigned to num4
>>> (num3,num4) = (10+5,20+5)
>>> print(num3)
15
>>> print(num4)
25

Nested Tuples

A tuple inside another tuple is called a nested tuple. In the program 10-1, roll number, name and marks (in percentage) of students are saved in a tuple. To store details of many such students we can create a nested tuple.

Program: This is a program to create a nested tuple to store roll number, name and marks of students

#To store records of students in tuple and print them
st=((101,"Aman",98),(102,"Geet",95),(103,"Sahil",87),(104,"Pawan",79))
print("S_No"," Roll_No"," Name"," Marks")
for i in range(0,len(st)):
print((i+1),'\t',st[i][0],'\t',st[i][1],'\t',st[i][2])

Output:

S_No Roll_No Name   Marks
1     101    Aman    98
2     102    Geet    95
3     103    Sahil   87
4     104    Pawan   79

Tuple Handling

Program: Write a program to swap two numbers without using a temporary variable.

#Program to swap two numbers
num1 = int(input('Enter the first number: '))
num2 = int(input('Enter the second number: '))
print("\nNumbers before swapping:")
print("First Number:",num1)
print("Second Number:",num2)
(num1,num2) = (num2,num1)
print("\nNumbers after swapping:")
print("First Number:",num1)
print("Second Number:",num2)

Output:

Enter the first number: 5
Enter the second number: 10
Numbers before swapping:
First Number: 5
Second Number: 10
Numbers after swapping:
First Number: 10
Second Number: 5

Program: Write a program to compute the area and circumference of a circle using a function.

#Function to compute area and circumference of the circle.
def circle(r):
area = 3.14*r*r
circumference = 2*3.14*r
#returns a tuple having two elements area and circumference
return (area,circumference)
#end of function
radius = int(input('Enter radius of circle: '))
area,circumference = circle(radius)
print('Area of circle is:',area)
print('Circumference of circle is:',circumference)

Output:

Enter radius of circle: 5
Area of circle is: 78.5
Circumference of circle is: 31.400000000000002

Program: Write a program to input n numbers from the user. Store these numbers in a tuple. Print the maximum and minimum number from this tuple.

#Program to input n numbers from the user. Store these numbers
#in a tuple. Print the maximum and minimum number from this tuple.
numbers = tuple() #create an empty tuple 'numbers'
n = int(input("How many numbers you want to enter?: "))
for i in range(0,n):
 num = int(input())
 #it will assign numbers entered by user to tuple 'numbers'
 numbers = numbers +(num,)
print('\nThe numbers in the tuple are:')
print(numbers)
print("\nThe maximum number is:")
print(max(numbers))
print("The minimum number is:")
print(min(numbers))

Output:

How many numbers do you want to enter?: 5
98
10
12
15
The numbers in the tuple are:
(9, 8, 10, 12, 15)
The maximum number is:
15
The minimum number is:
8