Lessons

Python Basics

Python Variables

Operators in Python

Conditional Statements in Python

Python Lists

Python Tuples

Python Sets

Python Dictionaries

Loops in Python

Python Arrays and Functions

Conclusion

List in Python

Python Lists

In Python, lists are versatile data structures used to store multiple items in a single variable. They are one of the four built-in data types for storing collections of data, alongside tuples, sets, and dictionaries. Each of these types has distinct qualities and usage scenarios.

1. Creating a List

Lists are created using square brackets [], and can contain any type of data, including strings, integers, and even other lists.

Example:

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mylist = ["apple", "banana", "cherry"]
print(mylist)

2. Characteristics of Lists

2.1. Ordered

Lists maintain a defined order for their elements. This means that when you add new items to a list, they will be placed at the end, preserving the sequence.

Example:

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thislist = ["apple", "banana", "cherry"]
print(thislist)  # Output: ['apple', 'banana', 'cherry']

2.2. Changeable

Lists are mutable, which means you can modify them after creation. You can change existing items, add new items, or remove items.

Example:

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thislist = ["apple", "banana", "cherry"]
thislist[1] = "orange"  # Changing the second item
print(thislist)  # Output: ['apple', 'orange', 'cherry']

2.3. Allow Duplicates

Lists can contain multiple items with the same value. This feature is useful for storing duplicate entries.

Example:

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thislist = ["apple", "banana", "cherry", "apple", "cherry"]
print(thislist)  # Output: ['apple', 'banana', 'cherry', 'apple', 'cherry']

3. List Length

You can determine the number of items in a list using the len() function.

Example:

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thislist = ["apple", "banana", "cherry"]
print(len(thislist))  # Output: 3

4. List Items - Data Types

List items can be of any data type. You can create lists containing strings, integers, booleans, or even other lists.

Example:

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list1 = ["apple", "banana", "cherry"]  # List of strings
list2 = [1, 5, 7, 9, 3]  # List of integers
list3 = [True, False, False]  # List of booleans

# A list with mixed data types:
mixed_list = ["abc", 34, True, 40, "male"

Checking Data Type

You can check the data type of a list using the type() function.

Example:

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mylist = ["apple", "banana", "cherry"]
print(type(mylist))  # Output: <class 'list'>

5. The List() Constructor

In addition to using square brackets, you can also create a list using the list() constructor.

Example:

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thislist = list(("apple", "banana", "cherry"))  # Note the double round-brackets
print(thislist)  # Output: ['apple', 'banana', 'cherry']

Frequently Asked Questions