DEV Community

Cover image for Python [ 'L', 'I', 'S', 'T' ]
Gaurav
Gaurav

Posted on

Python [ 'L', 'I', 'S', 'T' ]

Whether you are a Python beginneršŸ˜µ or a proficient Python Programmer/DeveloperšŸ¤©, one of the most common Data Structure that you will encounter is ListšŸ“ƒ

  • List, in Python, is an ordered, mutable, heterogeneous, dynamic Datatype.
  • They are ordered, so we can access individual elements through index.
  • They are mutable, means that the list elements can be updated.
  • A List can contain data of various datatypes like Integer, Float, Boolean, String etc.
  • List can contain duplicate elements.
  • Example of a list is
new_list = ["John", 2 , 2.5, True]

SimpleāœØšŸ’„......isn't it??!!!!!!šŸ˜ŽšŸ¤©

Okay..Let's discuss some of the most common methods that we can use upon Lists.

  • append()

    This method is used to add/append elements at the end of the list.

Syntax

list.append(element)

Example

num_list = ["John", 1, 2, 3, 4, True]
num_list.append(5)
print("Updated List: {}".format(num_list))

Output

Updated List: ['John', 1, 2, 3, 4, True, 5]
  • insert()

    This method is used to insert/add element at a specified location/index.

Syntax

list.insert(index, element)

Example

num_list = ["John", 1, 2, 3, 4, True]
num_list.insert(1,500)
print("Updated List: {}".format(num_list)

Output

Updated List: ["John", 500, 1, 2, 3, 4, True]

500 is inserted at index 1.

  • count()

    This method returns the number of occurrence of a particular element in a list.

Syntax

list.count(element)

Example

num_list = [1,2,3,5,4,5,6,5]
cnt = num_list.count(5)
print("Number of times 5 occur: {}".format(cnt))

Output

Number of times 5 occur: 3
  • sort()

    This method sorts the list in ascending order by default. To sort in descending order, we have to use reverse flag within the sort method.

Syntax

list.sort(reverse = True|False, key = function_name)

Example

num_list = [1,2,3,5,4,5,6,5]
num_list.sort()
print("Sorted List in Ascending Order: {}".format(num_list))
num_list.sort(reverse = True)
print("Sorted List in Descending Order: {}".format(num_list))

Output

Sorted List in Ascending Order: [1, 2, 3, 4, 5, 5, 5, 6]                                                                      
Sorted List in Descending Order: [6, 5, 5, 5, 4, 3, 2, 1]
  • reverse()

    As the name implies, this method reverses a list.

Syntax

list.reverse()

Example

num_list = [1,2,3,5,4,5,6,5]
num_list.reverse()
print("Reversed List: {}".format(num_list))

Output

Reversed List: [5, 6, 5, 4, 5, 3, 2, 1]
  • remove()

    This method removes a specified element from the list. If the specified element occurs more than once, then the first occurrence of the element is removed.

Syntax

list.remove(element)

Example

num_list = [1,2,3,5,4,5,6,5]
print("List before updating: {}".format(num_list))
num_list.remove(5)
print("Updated List: {}".format(num_list))

Output

List before updating: [1, 2, 3, 5, 4, 5, 6, 5]                                                                                
Updated List: [1, 2, 3, 4, 5, 6, 5]
  • pop()

    This method removes the element from the specified location/index.

Syntax

list.pop(index)

Example

num_list = [1,2,3,5,4,5,6,5]
print("List before updating: {}".format(num_list))
num_list.pop(5)
print("Updated List: {}".format(num_list))

Output

List before updating: [1, 2, 3, 5, 4, 5, 6, 5]                                                                                
Updated List: [1, 2, 3, 5, 4, 6, 5]
  • index()

    This method returns the index of a specified element. If the specified element occurs more than once, then index of the first occurrence of the element is returned.

Syntax

list.index(element)

Example

num_list = [1,2,3,5,4,5,6,5]
idx = num_list.index(5)
print("Index of 5: {}".format(idx))

Output

Index of 5: 3
  • extend()

    This method appends/adds the elements of any iterable (List, Set, Tuple, etc.) to the end of the current list.

Syntax

list.extend(iterable)

Example

num_list = [100,200,300,400,500]
char_list = ["A", "B", "C", "D"]
num_list.extend(char_list)
print("Updated List: {}".format(num_list))

Output

Updated List: [100, 200, 300, 400, 500, 'A', 'B', 'C', 'D']
  • copy()

    This method creates a copy of the specified list.

Syntax

list_2 = list_1.copy()

list_2 is the copy of list_1


Example

num_list = [100,200,300,400,500]
new_list = num_list.copy()
print("Copy of the 'num_list': {}".format(new_list))

Output

Copy of the 'num_list': [100, 200, 300, 400, 500]
  • clear()

    This method removes all the elements from the specified list.

Syntax

list.clear()

Example

num_list = [100,200,300,400,500]
num_list.clear()
print("Cleared List: {}".format(num_list))

Output

Cleared List: []

So...working with a List isn't that difficult!!....right???!!!!šŸ˜‡


Happy Learning!!āœŒšŸ˜Ž

Discussion (0)