How to access values in a list in Python?

In Python, values in a list can be retrieved using indexes. Each element in the list has a corresponding index, starting with 0 for the first element, 1 for the second, and so on. Indexes can be used to access specific elements in the list.

For example, suppose there is a list named my_list, you can use the following syntax to access specific elements:

my_list = [1, 2, 3, 4, 5]
print(my_list[0])  # 输出: 1
print(my_list[2])  # 输出: 3
print(my_list[-1])  # 输出: 5

In the example above, my_list[0] represents accessing the element at index 0 in the my_list list, which is the first element. Similarly, my_list[2] represents accessing the element at index 2, which is the third element. Using negative indexes, like my_list[-1], allows you to access elements starting from the end of the list in reverse order.

In addition to individual elements, subsets of lists can also be obtained using slicing. Slicing is done using the [start:end] format, where start is the starting index of the slice and end is the ending index of the slice (not inclusive). For example:

my_list = [1, 2, 3, 4, 5]
print(my_list[1:4])  # 输出: [2, 3, 4]

In the example above, my_list[1:4] means to retrieve elements from index 1 to index 3, which is the second to fourth element. Slicing can also omit the start or end to signify slicing from the beginning or end of the list, for example my_list[:3] means to retrieve the first three elements of the list.

These are the fundamental methods for accessing list values in Python, which can be used as needed to retrieve specific elements or subsets from the list.