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    You are at:Home»Programming»Python»How to Create and Read List in Python

    How to Create and Read List in Python

    By RahulMarch 22, 20233 Mins Read

    Python is a popular programming language with a vast range of applications, including data science, web development, and automation. One of the most basic and essential data structures in Python is the list. A list is a collection of values or items that can be of any data type, including strings, integers, floats, and even other lists.

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    In this article, we will explore how to create and read a list in Python.

    Creating a List

    To create a list in Python, we use square brackets [] and separate the items in the list using commas. Here is an example of a simple list:

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    my_list = [1, 2, 3, 4, 5]

    This list contains five integers, from 1 to 5. We can also create a list of strings, like this:

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    my_list = ['apple', 'banana', 'cherry']

    This list contains three strings, each representing a fruit.

    We can also create a list of different data types, like this:

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    my_list = [1, 'apple', 3.5, True]

    This list contains an integer, a string, a float, and a Boolean value.

    Another way to create a list is to use the list() constructor. We can pass any iterable object as an argument, such as a tuple or a string, and Python will create a list from it.

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    my_tuple = (1, 2, 3)
    my_list = list(my_tuple)
    print(my_list)  # Output: [1, 2, 3]
     
    my_string = "Hello, World!"
    my_list = list(my_string)
    print(my_list)  # Output: ['H', 'e', 'l', 'l', 'o', ',', ' ', 'W', 'o', 'r', 'l', 'd', '!']

    Reading a List

    Once we have created a list in Python, we can access its elements by their index. The index of the first element in a list is 0, and the index of the last element is the length of the list minus one. We can access an element by its index using square brackets [].

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    my_list = ['apple', 'banana', 'cherry']
    print(my_list[0])  # Output: 'apple'
    print(my_list[1])  # Output: 'banana'
    print(my_list[2])  # Output: 'cherry'

    We can also use negative indices to access elements from the end of the list.

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    my_list = ['apple', 'banana', 'cherry']
    print(my_list[-1])  # Output: 'cherry'
    print(my_list[-2])  # Output: 'banana'
    print(my_list[-3])  # Output: 'apple'

    We can access a range of elements in a list using the slice operator [:]. The slice operator returns a new list that includes all the elements from the start index up to, but not including, the end index.

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    my_list = ['apple', 'banana', 'cherry', 'date', 'elderberry']
    print(my_list[1:3])  # Output: ['banana', 'cherry']
    print(my_list[:3])  # Output: ['apple', 'banana', 'cherry']
    print(my_list[2:])  # Output: ['cherry', 'date', 'elderberry']

    We can also use the slice operator with negative indices.

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    my_list = ['apple', 'banana', 'cherry', 'date', 'elderberry']
    print(my_list[-3:-1])  # Output: ['cherry', 'date']

    Modifying a List

    In Python, we can modify the elements of a list. We can change an element by assigning a new value to its index.

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    my_list = ['apple', 'banana', 'cherry']
    my_list[1] = 'kiwi'
    print(my_list)  # Output: ['apple', 'kiwi', 'cherry']

    We can also add elements to a list using the append() method. The append() method adds a new element to the end of the list.

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    my_list = ['apple', 'banana', 'cherry']
    my_list.append('date')
    print(my_list)  # Output: ['apple', 'banana', 'cherry', 'date']

    We can insert an element at a specific index using the insert() method.

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    my_list = ['apple', 'banana', 'cherry']
    my_list.insert(1, 'date')
    print(my_list)  # Output: ['apple', 'date', 'banana', 'cherry']

    We can remove an element from a list using the remove() method. The remove() method removes the first occurrence of the specified value.

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    my_list = ['apple', 'banana', 'cherry']
    my_list.remove('banana')
    print(my_list)  # Output: ['apple', 'cherry']

    We can also remove an element from a specific index using the pop() method. The pop() method removes the element at the specified index and returns it.

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    my_list = ['apple', 'banana', 'cherry']
    banana = my_list.pop(1)
    print(banana)  # Output: 'banana'
    print(my_list)  # Output: ['apple', 'cherry']

    Conclusion

    Lists are an essential data structure in Python that allows us to store and manipulate collections of values. We can create lists using square brackets [] or the list() constructor. We can access list elements using their index, and we can modify lists by changing, adding, or removing elements. Understanding how to create and read a list is fundamental to writing Python programs, and these skills will be useful in many applications.

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