Appending elements to an array is a frequent operation and Python provides several ways to do it. Unlike lists, arrays are more compact and are designed for more efficient numerical computation. In this article, we will explore different methods for appending to an array.

Using append() Method

The simplest and most commonly used method to append an element to an array in Python is by using append() method. It’s straightforward and works in-place, meaning it modifies the original array directly.

import array

# Create an array
arr = array.array('i', [1, 2, 3])

# Append an element
arr.append(4)

print(arr)  

array('i', [1, 2, 3, 4])

This is generally the most efficient and simple method for appending one element to an array.

Let's take a look at other methods of appending to an array in python:

Using extend() Method

If you want to append multiple elements (i.e., extend the array with another iterable), the extend() method is your best choice. It appends all the elements from the iterable to the array.

import array

# Create an array
arr = array.array('i', [1, 2, 3])

# Extend the array with multiple elements
arr.extend([4, 5, 6])

print(arr)  

array('i', [1, 2, 3, 4, 5, 6])

This method is perfect for when you need to append multiple elements in a single operation.

Using Array Concatenation (+ Operator)

You can also append to an array by concatenating it with another array or iterable using the + operator. This method creates a new array by combining the original array and the new elements.

import array

# Create an array
arr = array.array('i', [1, 2, 3])

# Concatenate arrays
arr = arr + array.array('i', [4, 5])

print(arr)  

array('i', [1, 2, 3, 4, 5])

While concatenation is simple and effective for combining arrays, it’s less efficient than extend() for appending multiple elements to an existing array.

Using a Loop

If you want to append multiple elements one by one, you can use a loop. Although this is less efficient than other methods, it gives you full control over how the elements are added.

import array

# Create an array
arr = array.array('i', [1, 2, 3])

# Append elements using a loop
for i in range(4, 7):
    arr.append(i)

print(arr)  

array('i', [1, 2, 3, 4, 5, 6])

This method is more flexible but slower than using extend() when appending multiple elements.

Using fromlist() Method

The fromlist() method can be used to append elements from a list to an array. It's similar to extend(), but it’s specifically designed for lists and arrays.

import array

# Create an array
arr = array.array('i', [1, 2, 3])

# Append elements from a list using fromlist()
arr.fromlist([4, 5, 6])

print(arr)  

array('i', [1, 2, 3, 4, 5, 6])

This method is great for appending from lists, but for general cases, extend() is often better.