How to convert a list of integers into a single integer in Python

In this tutorial, we will explore various approaches to convert a list of integers into a single integer. This involves converting a list containing multiple integers, such as [1, 2, 3, 4, 5], into a single integer representation, which would be 12345. There are multiple methods available to achieve this conversion, and we will discuss some of them in detail. By the end of this tutorial, you will have a good understanding of different techniques to transform a list of integers into a single integer value.

To convert the entire list into one integer in Python, you can:

  1. Concatenate list of integers using string concatenation
  2. Apply join() method along with map() method or list comprehension to convert each item in the list into a single integer value

By implementing these steps, you can effectively convert the entire list into a single integer in Python.

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Concatenate a list of integers using string concatenation

To concatenate a list of numbers into a single string, you can use a loop to iterate over the list. Then, add all the elements into a variable using string concatenation. The str() function can be used to convert variables of any data type to a string. Here’s an example code that demonstrates this approach:

#Using String Concatenation

# declaring a list
List1 = [1, 2, 3, 4, 5]  

# create a variable to store final integer
var = '' "

#iterate over the list elements
for element in List1: 
    # converting integer to string and adding into variable
    var += str(element)

# converting back into integer and printing the final result



In this code, we start with an empty string var. The loop iterates over each element in the list “list1“. We convert each number to a string using the str() function and then concatenate it with the var string. After the loop completes, we have a single string that contains all the numbers from the list. Then, using int(), we converted var back to an integer and printed the final result.

The code effectively converts the list of numbers [1, 2, 3, 4, 5] into a single integer 12345 and outputs it.

Apply the join() method along with map() method or list comprehension

When we have a list of numbers and we want to concatenate them into a single string, the join() function can be a useful tool. However, it operates on strings, so we need to convert the numbers in the list into strings before using join(). This can be accomplished using either map() method or list comprehension.

The map() function takes two arguments: the input list and the desired data type. By applying the map() function with the str() function as the desired data type, the list of integers can be converted into a list of strings in a more efficient manner. Here’s an example:

# Using map() with join() function to convert a list of multiple integers into a single integer

# create a list
List1 = [7, 9, 1, 4, 5]  

# converting the items of list1 into string using map function, join them and then convert the final result to integer datatype
new_integer = int(''.join(map(str, List1))) 

# print the final result
print("Result: ", new_integer)


Result: 79145

In this code, the map() function is used to apply the str() function to each element in List1, resulting in a list of strings. These strings are then joined together using the join() function without any separator, creating a single string. Finally, the resulting string is converted to an integer using the int() function and stored in the variable new_integer.

In the previous method, the process of converting a list of integers into a string involved iterating over the list and converting each integer to a string individually. The map() function eliminates the need for explicit iteration, thus providing a more concise and efficient solution.

You can also use list comprehension instead of a map() function. It allows us to iterate over the list and apply a transformation to each element as shown in the code snippet below

#Using Join Function to convert a list of multiple integers into a single integer

# declare a list
List1 = [9, 5, 3, 6, 7, 2, 4]  

# converting integers to strings
List1 = [str(element) for element in List1]  

# joining all the elements and converting it back into integer
new_integer = int(''.join(List1))

# printing the result



The above code converts each integer in the list to a string using list comprehension. The join() function is applied to concatenate these string elements without any separator. The resulting concatenated string is then converted back to an integer using the int() function.

This approach allows for a concise and efficient way to merge the individual integers into a single integer representation.


In this tutorial, we explored different methods to convert a list of integers into a single integer representation in Python such as using string concatenation or join function. We utilized the join() function along with either the map() function or list comprehension to convert the integers into strings and then join them into a single string. These techniques provide various approaches to achieve the desired conversion, giving you flexibility in choosing the method that best suits your needs. By understanding these methods, you now have the knowledge to efficiently convert a list of integers into a consolidated single integer value in Python.

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