Master Python Lists: Create, Access, and Slice Elements with Easy Examples

1. Introduction

In Python programming, lists are frequently used. For example, to store the total scores of 50 students, using a list is far more convenient than defining 50 separate variables.

2. Getting to Know Lists

Unlike C or Java, which have arrays, Python provides lists. A list stores elements inside square brackets [] separated by commas, e.g.:

listName = [element1, element2, element3, ... elementN]

Lists can hold elements of the same type or different types, unlike C arrays which require the same type. Example:

listName = [1, 'a']

3. Creating Lists

There are two ways to create a list:

1) Using square brackets:

listName = [element1, element2, element3, ... elementN]

Example:

a = [1, 2, 3, 4, 5]
b = ["Python", "Java", "C语言"]

2) Using the list() function to convert a tuple or string into a list: listName = list(a) Example:

a = ('Java', 10, 'Python', 'PHP', 20)
list1 = list(a)
print("list1列表中元素有: ", list1)

b = "This is Python"
list2 = list(b)
print("list2列表中元素有: ", list2)

Resulting output:

4. Accessing List Elements

Two methods are available:

1) Indexing by position (starting at 0):

listName = ['A', 'B', 'C', 'D']  # define a list
element = listName[i]           # access element at index i

2) Slicing:

listName = ['A', 'B', 'C', 'D']
sublist = listName[start:end:step]  # start, end, step

Example demonstrating various slices:

listName = ['A','B','C','D','E','F','G']
print(listName[1:3])      # ['B', 'C']
print(listName[3:])      # ['D','E','F','G']
print(listName[1:6:2])   # ['B','D','F']
print(listName[-5:-2])   # ['C','D','E']

Output:

5. Summary

This article introduced what a Python list is and how to create and access its elements. It covered list creation using brackets and the list() function, and demonstrated element access via indexing and slicing with practical code examples.