Joining Arrays in Python: Merging and Concatenation Methods

Discover how to join or merge two arrays in Python using methods like append() and extend(). Learn the best practices for concatenating arrays and ensuring data type compatibility to avoid errors.

Python - Join Arrays

Joining two arrays is also known as merging or concatenating. Python provides multiple ways to merge two arrays, such as using append() and extend() methods. Before merging, ensure that both arrays are of the same data type to avoid errors.

In Python, an array is a homogeneous collection of built-in data types like strings, integers, or floats. The array itself is not a built-in type, so we use Python's built-in array module.

Merge Python Array

Join two Arrays in Python

To join arrays in Python, you can use the following approaches:

• Using append() method
• Using + operator
• Using extend() method

Using append() Method

To join two arrays, append each item from one array to another using the append() method. Run a for loop on the original array, fetch each element, and append it to a new array.

import array as arr

# creating two arrays
a = arr.array('i', [10, 5, 15, 4, 6, 20, 9])
b = arr.array('i', [2, 7, 8, 11, 3, 10])

# merging both arrays
for i in range(len(b)):
a.append(b[i])
print(a)

array('i', [10, 5, 15, 4, 6, 20, 9, 2, 7, 8, 11, 3, 10])

Using + Operator

We can also use the + operator to concatenate or merge two arrays. First, convert arrays to list objects, concatenate the lists using the + operator, and convert back to get the merged array.

import array as arr

a = arr.array('i', [10, 5, 15, 4, 6, 20, 9])
b = arr.array('i', [2, 7, 8, 11, 3, 10])
x = a.tolist()
y = b.tolist()
z = x + y
a = arr.array('i', z)
print(a)

array('i', [10, 5, 15, 4, 6, 20, 9, 2, 7, 8, 11, 3, 10])

Using extend() Method

Another approach to concatenate arrays is the use of the extend() method from the List class. First, convert the array to a list, then call the extend() method to merge the two lists.

import array as arr

a = arr.array('i', [88, 99, 77, 66, 44, 22])
b = arr.array('i', [12, 17, 18, 11, 13, 10])
a.extend(b)
print(a)

array('i', [88, 99, 77, 66, 44, 22, 12, 17, 18, 11, 13, 10])