Join a List of Integers into a String in Python

# Table of Contents

1. Join a list of integers into a string in Python
2. Join a list of integers into a string using a generator expression
3. Join a list of integers into a string using a list comprehension
4. Join a list of integers into a string using a for loop

# Join a list of integers into a string in Python

To join a list of integers into a string:

1. Use the map() function to convert the integers in the list to stings.
2. Call the str.join() method on a string separator.
3. Pass the map object to the join() method.

Copied!
my_list = [1, 2, 3, 4, 5]

my_str = ', '.join(map(str, my_list))

print(my_str)  # 👉️ "1, 2, 3, 4, 5"

The str.join() method takes an iterable as an argument and returns a string which is the concatenation of the strings in the iterable.

The map() function takes a function and an iterable as arguments and calls the function with each item of the iterable.

Copied!
my_list = [1, 2, 3, 4, 5]

# 👇️ ['1', '2', '3', '4', '5']
print(list(map(str, my_list)))

We simply passed each integer to the str() class to get a map object that only contains strings.

The string the join() method is called on is used as the separator between elements.

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my_list = [1, 2, 3, 4, 5]

my_str = '-'.join(map(str, my_list))

print(my_str)  # 👉️ "1-2-3-4-5"

If you don't need a separator and just want to join the iterable's elements into a string, call the join() method on an empty string.

Copied!
my_list = [1, 2, 3, 4, 5]

my_str = ''.join(map(str, my_list))

print(my_str)  # 👉️ "12345"

This approach also works if your list contains both strings and integers.

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my_list = [1, 'a', 2, 'b', 3, 'c', 4, 'd', 5]

my_str = ', '.join(map(str, my_list))

print(my_str)  # 👉️ "1, a, 2, b, 3, c, 4, d, 5"

Alternatively, you can pass a generator expression to the join() method.

# Join a list of integers into a string using a generator expression

This is a three-step process:

1. Call the join() method on a string separator.
2. Pass a generator expression to the join() method.
3. On each iteration, pass the list item to the str() class to convert it to a string.

Copied!
my_list = [1, 2, 3, 4, 5]


result = ', '.join(str(item) for item in my_list)

print(result)  # 👉️ "1, 2, 3, 4, 5"

We used a generator expression to convert each item to a string by passing it to the str() class.

# Join a list of integers into a string using a list comprehension

A list comprehension can also be used in place of a generator expression.

Copied!
my_list = [1, 2, 3, 4, 5]


result = ', '.join([str(item) for item in my_list])

print(result)  # 👉️ "1, 2, 3, 4, 5"

The code sample is very similar to the previous one, however, we used a list comprehension.

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my_list = [1, 2, 3, 4, 5]

list_of_strings = [str(item) for item in my_list]
print(list_of_strings)  # 👉️ ['1', '2', '3', '4', '5']

print('-'.join(list_of_strings)) # 👉️ 1-2-3-4-5

On each iteration, we convert the current integer to a string and return the result.

# Join a list of integers into a string using a for loop

A for loop can also be used to convert the list of integers to a list of strings before joining them.

Copied!
my_list = [1, 2, 3, 4, 5]

list_of_strings = []

for item in my_list:
    list_of_strings.append(str(item))

my_str = ', '.join(list_of_strings)

print(my_str) # 👉️ "1, 2, 3, 4, 5"

We declared a new variable that stores an empty list and used a for loop to iterate over the original list.

On each iteration, we convert the current item to a string and append the result to the new list.

The last step is to join the list of strings with a separator.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Join the Keys or Values of Dictionary into String in Python
• Join a List with a Newline character in Python