Introduction to Python : Lists

Lists

A list in Python is a compound data type for storing a sequence of values or elements. A list is created by placing its elements in a square bracket ([]) separated by commas. Example

# A list of strings
sample_list = ["Apple", "Mango", "Orange"] 

A list can contain elements of different data types

# A list of mixed data types
mixed_list = ["Apple", 10, 3.6]

A list may also be empty

# An empty list
empty_list = []

The individual elements of a list can accessed by zero-based indexing. The first element in a list has an index 0, the next has an index 1 and so on. Examples:

sample_list = ["Apple", "Mango", 12, 10.5]
print(sample_list[0])
print(sample_list[2])

Outputs:

Apple

12

 

Negative integers starting from -1 can be used to access elements in a list from the end.

sample_list = ["Apple", "Mango", 12, 10.5]
print(sample_list[-1])

Output:

10.5

sample_list = ["Apple", "Mango", 12, 10.5]
print(sample_list[-3])

Output:

Mango

 

Lists in Python are not immutable. New elements can be added to and existing elements can be removed from lists. Also elements in lists may be replaced. To add a new element to a list, use the 'append' function on the list.

sample_list = ["Apple", "Mango", 12, 10.5]
sample_list.append("Orange")
print(sample_list)

Output:

['Apple', 'Mango', 12, 10.5, 'Orange'] 

 

To replace the element 12 with 17:

sample_list = ["Apple", "Mango", 12, 10.5]
sample_list[2] = 17
print(sample_list)

Output:

['Apple', 'Mango', 17, 10.5]

 

To delete an element from a list:

sample_list = ["Apple", "Mango", 12, 10.5]
del sample_list[1]
print(sample_list)

Output:

['Apple', 17, 10.5] 
 


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Introduction to Python
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