Every NumPy array has elements and their respective indices. Here we will focus on indices in 1D arrays. Let's take a look at the following image:

Here we have an array of five elements: [9, 6, 4, 8, 10]. Every element has a positive and negative index. For example, 9 has 0 as its positive index and -5 as its negative index. As you can see, positive indexing in arrays starts at 0 and goes up to n-1, where n is the length of the array. Negative indexing, on the other hand, starts at -n and goes up to -1.

Accessing Elements by Indices

To access an element by its index, you should specify the index of this element in square brackets, e.g., array[2].

Note

If a specified index is out of bounds, an IndexError is thrown, so be cautious of that.

Let's take a look at an example:

As you can see, there is nothing complicated here.

Note

It is common practice to access the first element of the array using a positive index (0) and the last element using a negative index (-1).

Since the elements of our array are just numbers, we can perform all kinds of operations on them that we would do with regular numbers:

Here, we calculated the average of the first and the last elements of our array.