Chapter 10 : Tuples and Dictionaries | class 11th | revision notes computer science

Tuples Manipulation in Python – Notes

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Topics:

• Tuples:
  • Introduction,
  • indexing,
  • tuple operations (concatenation, repetition, membership & slicing),
  • built-in functions: len(), tuple(), count(), index(), sorted(), min(), max(), sum();
  • tuple assignment,
  • nested tuple,
• Suggested programs:
  • finding the minimum,
  • maximum, mean of values stored in a tuple;
  • linear search on a tuple of numbers,
  • counting the frequency of elements in a tuple

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What is Tuple?

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.

# 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 i.e. tuple inside the tuple
       >>> tuple4 = (1,2,3,4,5,(10,20))
       >>> tuple4
       (1, 2, 3, 4, 5, (10, 20))         

Tuple having Single Element:

If there is only a single element in a tuple then the element should be followed by a comma.

Note : If we assign the value without comma it is treated as integer.

# 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 

# tuple6 is assigned a single element
      >>> tuple6 = (20,) #element followed by comma
      >>> tuple6
       (20,)
      >>> type(tuple5)   #tuple6 is of type tuple
      <class 'tuple'>    #it is treated as tuple                

Tuple created without parenthesis ( ) :

A sequence of without parenthesis i.e. values separated with comma is treated as tuple by default.

# 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)  

# A sequence having different types of values
    >>> seq = 1, "www.anjeevsinghacademy.com", 2, "www.mycstutorial.in"
    >>> type(seq)
    <class 'tuple'>   
    >>> print(seq)
    (1, 'www.anjeevsinghacademy.com', 2, 'www.mycstutorial.in')                

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.

 # Creating / Initializes a tuple tuple1       
 >>> tuple1 = (2,4,6,8,10,12)          
 # Accessing the first element of tuple1
 >>> tuple1[0]
 2
 # Accessing the fourth element of tuple1
 >>> tuple1[3]
 8
# an expression resulting in an integer index
 >>> tuple1[1+4]
 12

 # Backward Accessing 
 
 # Accessing the first element from right
 >>> tuple1[-1]
 12 
 # Accessing the third element from right
 >>> tuple1[-3]
 8       
 # Index out of range : If invalid index is given then python raise an error message - IndexError : Index out of      
   range. 

#returns error as index is out of range
 >>> tuple1[15]
 IndexError: tuple index out of range       

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         

Elements of Tuple is Mutable (If element is a list)

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])         

List vs Tuple:

• List is mutable but tuple is immutable. So iterating through a tuple is faster as compared to a list.
• If we have data that does not change then storing this data in a tuple will make sure that it is not changed accidentally.

Tuple Operations

1. Concatenation (+)

Python allows us to join tuples using concatenation operator depicted by symbol +.

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

Create a new tuple which contains the result of this concatenation operation.

  >>> 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.

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

2. Repetition / Replication Operator *

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')         

3. Membership operator [ in and not in ]

in : 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         

not in : 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         

4. Slicing

Slicing means extracting the parts of list. Like string and list, slicing can be applied to tuples in the same way.

Forward Slicing

 # 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)         

Backward Slicing / Negative Indexing

 # slice in reverse of the tuple
   >>> tuple1[::-1]
   (80, 70, 60, 50, 40, 30, 20, 10) 
   
   >>> tuple1[-1: -(len(tuple)+1):-1]
   (80, 70, 60, 50, 40, 30, 20, 10) 
 # slice in reverse alternate element of the tuple
   >>> tuple1[-1: -(len(tuple)+1):-2]
   (80,60,40,20)  
 # negative indexing
   >>> tuple1[-6:-4]
   (30, 40)          

Tuple Methods and Built-in Functions

1. len() : Returns the length or the number of elements of the tuple passed as the argument

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

2. tuple() : Creates an empty tuple if no argument is passed. Creates a tuple if a sequence is passed as argument

>>> 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)

3. count() : Returns the number of times the given element appears in the tuple.

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

4. index() : Returns the index of the first occurrence of the element in the given tuple.

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

5. sorted() : Takes elements in the tuple and returns a new sorted list. It should be noted that, sorted() does not make any change to the original tuple

tuple1 = (“Rama”,”Heena”,”Raj”,
“Mohsin”,”Aditya”)
sorted(tuple1)
[‘Aditya’, ‘Heena’, ‘Mohsin’, ‘Raj’,
‘Rama’]

6. min() : Returns minimum or smallest element of the tuple.

7. max() : Returns maximum or largest element of the tuple.

8. sum() : Returns sum of the elements of the tuple.

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

Tuple Assignment :

Assignment of tuple is 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.

# 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)

Tuple Unpacking :

Tuple Unpacking means, assigning values of tuple elements to different variables. Variables are written left of assignment operator separated by comma and tuple is written on the right side of assignment operator.

Be ensure, number of variables must be equal to the number of elements of tuple. Otherwise Python raise ValueError: not enough values to unpack.

>>> 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)

Nested Tuples

A tuple inside another tuple is called a nested tuple.

>>> nestedtuple = ( (1,2,3), (4,5,6), (7,8,9))
>>> nestedtuple
((1, 2, 3), (4, 5, 6), (7, 8, 9))
>>> nestedtuple[0]
(1, 2, 3)
>>> nestedtuple[1]
(4, 5, 6)
>>> nestedtuple[2]
(7, 8, 9)
>>> nestedtuple[0][0]
1
>>> nestedtuple[0][1]
2
>>> nestedtuple[2][1]
8
>>> print(nestedtuple)
((1, 2, 3), (4, 5, 6), (7, 8, 9))

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

 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 : 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 = 3.14rr
     circumference = 23.14r
     return (area,circumference) 
     #returns a tuple having two elements area and 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.

 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