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ADDING NEW ELEMENTS IN THE LISTS

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ADDING NEW ELEMENTS IN THE LISTS

INTRODUCTION

Python has provided us a group of built-in methods for List manipulation. Below are the methods for adding new elements in the list.

append() method

append() method is used to add a new element in the list. By using append() method we can add only one record at a time. If we add multiple records at a time then Python will raise error.

# append() method example 1

str_list = ['Python', 'Java', 'C++', 'C', 'PHP', 'XML'] 
print("\nElement of list str_list ->", str_list) 

str_list.append('Word')
print("\nRevised element of list str_list ->", str_list)

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML']

Revised element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML', 'Word']

In the above example, we have added one new element Word in the list using append() method.

# append() method example 2

int_list = [4, 2, 6, 10, 15, 20] 
print("\nElement of list int_list ->", int_list) 

int_list.append(12)
print("\nRevised element of list int_list ->", int_list)

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list int_list -> [4, 2, 6, 10, 15, 20]

Revised element of list int_list -> [4, 2, 6, 10, 15, 20, 12]

In the above example, we have added one new element 12 in the list using append() method.

Now we are adding multiple elements by calling append() method multiple times.

# append() method example 3

str_list = ['Python', 'Java', 'C++', 'C', 'PHP', 'XML'] 
print("\nElement of list str_list ->", str_list) 

str_list.append('Word')
print("\nRevised element of list str_list ->", str_list) 

str_list.append('Excel')
str_list.append('VB .Net')
print("\nRevised element of list str_list ->", str_list)

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML']

Revised element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML', 'Word']

Revised element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML', 'Word', 'Excel', 'VB .Net']


# append() method example 4

int_list = [4, 2, 6, 10, 15, 20] 
print("\nElement of list int_list ->", int_list) 

int_list.append(12)
print("\nRevised element of list int_list ->", int_list)

int_list.append(5)
int_list.append(7)
print("\nRevised element of list int_list ->", int_list)

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list int_list -> [4, 2, 6, 10, 15, 20]

Revised element of list int_list -> [4, 2, 6, 10, 15, 20, 12]

Revised element of list int_list -> [4, 2, 6, 10, 15, 20, 12, 5, 7]

If we try to pass multiple values in the append() method then Python will raise an error.

# append() method example 5

str_list = ['Python', 'Java', 'C++', 'C', 'PHP', 'XML'] 
print("\nElement of list str_list ->", str_list) 

str_list.append('Word')
print("\nRevised element of list str_list ->", str_list) 

str_list.append('Excel', 'VB .Net')
print("\nRevised element of list str_list ->", str_list)

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML']

Revised element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML', 'Word']
Traceback (most recent call last):
  File "d:\PYTHON\PROGRAM\tempCodeRunnerFile.python", line 13, in <module>
    str_list.append('Excel', 'VB .Net')
TypeError: list.append() takes exactly one argument (2 given)


# append() method example 6

int_list = [4, 2, 6, 10, 15, 20] 
print("\nElement of list int_list ->", int_list) 

int_list.append(12)
print("\nRevised element of list int_list ->", int_list)

int_list.append(5, 7)
print("\nRevised element of list int_list ->", int_list)

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list int_list -> [4, 2, 6, 10, 15, 20]

Revised element of list int_list -> [4, 2, 6, 10, 15, 20, 12]
Traceback (most recent call last):
  File "d:\PYTHON\PROGRAM\tempCodeRunnerFile.python", line 13, in <module>
    int_list.append(5, 7)
TypeError: list.append() takes exactly one argument (2 given)

insert() method

insert() method allows us to add one element in a specific position in the list. If we add the element in the middle of a list then it will shift the previous element of that position to the right.

# insert() method example 1

str_list = ['Python', 'Java', 'C++', 'C', 'PHP', 'XML'] 
print("\nElement of list str_list ->", str_list) 
print("\nCount of element of list str_list ->", len(str_list)) 

str_list.insert(2, 'Word')
print("\nRevised element of list str_list ->", str_list) 
print("\nCount of element of list str_list ->", len(str_list)) 

str_list.insert(4, 'Excel')
print("\nRevised element of list str_list ->", str_list) 
print("\nCount of element of list str_list ->", len(str_list))

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML']

Count of element of list str_list -> 6

Revised element of list str_list -> ['Python', 'Java', 'Word', 'C++', 'C', 'PHP', 'XML']

Count of element of list str_list -> 7

Revised element of list str_list -> ['Python', 'Java', 'Word', 'C++', 'Excel', 'C', 'PHP', 'XML']

Count of element of list str_list -> 8

In the above example, we can see that we have added the Word element at the position 2 starting from 0. Earlier C++ was at position 2 but after inserting Word, C++ has been shifted to the right. Similarly, Excel element was inserted at position 4. Earlier C was at position 4 which is now replaced by Excel and shifted to the right.

# insert() method example 2

int_list = [400, 200, 600, 100, 150, 200] 
print("\nElement of list int_list ->", int_list) 

int_list.insert(3, 120)
print("\nRevised element of list int_list ->", int_list)

int_list.insert(5, 700)
print("\nRevised element of list int_list ->", int_list)

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list int_list -> [400, 200, 600, 100, 150, 200]

Revised element of list int_list -> [400, 200, 600, 120, 100, 150, 200]

Revised element of list int_list -> [400, 200, 600, 120, 100, 700, 150, 200]

In the above example, 120 has been inserted at the index position 3 where 100 was placed earlier. Now 100 has been shifted to the right. Then 700 has been inserted at the index position 5 where 150 was placed earlier. Now 150 has been shifted to the right.

extend() method

If we want to add more than elements at a time in a list, then we will use the extend() method.

# extend() method example 1

str_list = ['Python', 'Java', 'C++', 'C', 'PHP', 'XML'] 
print("\nElement of list str_list ->", str_list) 
print("\nCount of element of list str_list ->", len(str_list)) 

str_list.extend(['Word', 'Excel'])
print("\nRevised element of list str_list ->", str_list) 
print("\nCount of element of list str_list ->", len(str_list))

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML']

Count of element of list str_list -> 6

Revised element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML', 'Word', 'Excel']

Count of element of list str_list -> 8

In the above example, we have added two elements Word and Excel at a time by using extend() method.

# extend() method example 2

int_list = [400, 200, 600, 100, 150, 200] 
print("\nElement of list int_list ->", int_list) 
print("\nNumber of element in the list int_list ->", len(int_list))

int_list.extend([300, 120, 700])
print("\nRevised element of list int_list ->", int_list)
print("\nRevised Number of element in the list int_list ->", len(int_list))

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list int_list -> [400, 200, 600, 100, 150, 200]

Number of element in the list int_list -> 6

Revised element of list int_list -> [400, 200, 600, 100, 150, 200, 300, 120, 700]

Revised Number of element in the list int_list -> 9

In the above example, we have added 3 new elements 300, 120, 700 by using extend() method.

Addition Operator(+)

We can use addition operator to add new elements in an existing list.

# Addition operator example 1

str_list = ['Python', 'Java', 'C++', 'C', 'PHP', 'XML'] 
print("\nElement of list str_list ->", str_list) 
print("\nCount of element of list str_list ->", len(str_list)) 

str_list_new = ['Word', 'Excel']
str_list = str_list + str_list_new
print("\nRevised element of list str_list ->", str_list) 
print("\nCount of element of list str_list ->", len(str_list))

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML']

Count of element of list str_list -> 6

Revised element of list str_list -> ['Python', 'Java', 'C++', 'C', 'PHP', 'XML', 'Word', 'Excel']

Count of element of list str_list -> 8

In the above example, we can see that we have created one list variable str_list. Then another list variable str_list_new is created and its elements are included in the list list_str.

# Addition operator example 2

int_list = [400, 200, 600, 100, 150, 200] 
print("\nElement of list int_list ->", int_list) 
print("\nNumber of element in the list int_list ->", len(int_list))

int_list_new = [300, 120, 700]
int_list = int_list + int_list_new
print("\nRevised element of list int_list ->", int_list)
print("\nRevised Number of element in the list int_list ->", len(int_list))

ADDING NEW ELEMENTS IN THE LISTS : Output

Element of list int_list -> [400, 200, 600, 100, 150, 200]

Number of element in the list int_list -> 6

Revised element of list int_list -> [400, 200, 600, 100, 150, 200, 300, 120, 700]

Revised Number of element in the list int_list -> 9

In the above example, we can see that, the list int_list_new has been added with list int_list using addition operator (+). Finally, the list int_list is showing the combined data of int_list and int_list_new.

ADDING NEW ELEMENTS IN THE LISTS : Output

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