Python list is a data structure which is used to store various types of data. Python list is a indexed collection of elements of same or different type referred by same name.

Python list is a data structure which is used to store various types of data.

A list can be composed by storing a sequence of different type of values separated by commas.

Python list is enclosed between square([]) brackets and elements are stored in the index basis with starting index 0.

  • Creating and Accessing the List

    n Python programming, a list is created by placing all the items (elements) inside a square bracket [ ], separated by commas.

    Example)
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    # empty list
    my_list = []
    
    # list of integers
    my_list = [1, 2, 3]
    
    # list with mixed datatypes
    my_list = [1, "Hello", 3.4]

    Example of creating list

    
    # creating the list containing numbers
    numbers = [1, 2, 3, 4, 5, 6]
    print(numbers)
    days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday']
    print(days)
    both_day_and_numbers=[1,2,3,'this', 'is', 'for', 'testing', 'purpose']
    print(both_day_and_numbers)

    Output:
    [1, 2, 3, 4, 5, 6]
    ['Monday', 'Tuesday', 'Wednesday', 'Thursday']
    [1, 2, 3, 'this', 'is', 'for', 'testing', 'purpose']
    
  • How to access elements from a list?

    We can use the index operator [] to access an item in a list. Index starts from 0. So, a list having 5 elements will have index from 0 to 4.

    • Trying to access an element other that this will raise an IndexError . The index must be an integer. We can't use float or other types, this will result into TypeError.

    Example)
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    days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday']
    print(days[0])
    print(days[1])
    print(days[2])
    print("===================")
    # printing the values using for loop
    for day in days:
        print(day)
    
    Output:
    Monday
    Tuesday
    Wednesday
    ===================
    Monday
    Tuesday
    Wednesday
    Thursday
    
  • Negative indexing

    Python allows negative indexing for its sequences. The index of -1 refers to the last item, -2 to the second last item and so on.

    Example)
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    days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday']
    print(days[-1])
    print(days[-2])
    Output:
    Thursday
    Wednesday
    
  • Slice lists in Python

    We can access a range of items in a list by using the slicing operator (colon).


    Example of slicing

    
    days = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']
    # Going to slice the list days
    print(days[0:3])  # 3rd position is excluded
    print(days[3:6])  # start 3 to 6-1
    print(days[2:])  # start from 0 to end
    print(days[:5])  # elements start from 0 to 5-1
    print(days[0:6:2])  # 3rd argument specifies the steps
    print(days[:-1])  # -1 is last index
    

    Output:
    ['Monday', 'Tuesday', 'Wednesday']
    ['Thursday', 'Friday', 'Saturday']
    ['Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']
    ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday']
    ['Monday', 'Wednesday', 'Friday']
    ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
  • Python List Methods

    Methods that are available with list object in Python programming are tabulated below. They are accessed as list.method(). Some of the methods have already been used above.

    Method Description
    append(element) Add an element to the end of the list
    extend(sequence) Add all elements of a list to the another list
    insert(index,element) Insert an item at the defined index
    remove() Removes an item from the list
    pop(index)/pop Removes and returns an element at the given index
    index(object) Returns the index of the first matched item
    reverse() Reverse the order of items in the list
    sort() Sort items in a list in ascending order
    count() Returns the count of number of items passed as an argument
    clear() Removes all items from the list

What next?

The next topic is Python Tuple

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