[Tut] How to Print a List Without Commas in Python

How to Print a List Without Commas in Python

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Problem Formulation

Given a Python list of elements.

If you print the list to the shell using print([1, 2, 3]), the output is enclosed in square brackets and separated by commas like so:

[1, 2, 3]

But you want the list without commas like so:

[1 2 3]

print([1, 2, 3])

# Output: [1, 2, 3]

# Desired: [1 2 3]

How to print the list without separating commas in Python?

Note that this is slightly different to those two problem variants—feel free to click there to learn more about those problem variants:

Recommended Tutorial: How to Print a List Without Brackets and Commas in Python?

Recommended Tutorial: How to Print a List Without Brackets in Python?

Method 1: Unpacking Multiple Values into Print Function

The asterisk operator * is used to unpack an iterable into the argument list of a given function.

You can unpack all list elements into the print() function to print all values individually, separated by an empty space per default (that you can override using the sep argument). For example, the expression print('[', *lst, ']') prints the elements in my_list, empty space separated, with the enclosing square brackets and without the separating commas!

Here’s an example:

lst = [1, 2, 3]

print('[', *lst, ']')

# [ 1 2 3 ]

You can learn about the ins and outs of the built-in print() function in the following video:

To master the basics of unpacking, feel free to check out this video on the asterisk operator:

Method 2: String Replace Method

A simple way to print a list without commas is to first convert the list to a string using the built-in str() function. Then modify the resulting string representation of the list by using the string.replace() method until you get the desired result.

Here’s an example:

my_list = [1, 2, 3] # Convert List to String

s = str(my_list)

print(s)

# [1, 2, 3] # Replace Separating Commas

s = s.replace(',', '') # Print List Without Commas

print(s)

# [1 2 3]

The last line of the code snippet shows that the commas are removed from the output.

Method 3: String Join With Generator Expression

You can print a list without commas using the string.join() method on any separator string such as ' ' or '\t'. Pass a generator expression to convert each list element to a string using the str() built-in function.

Specifically, the expression print('[', ' '.join(str(x) for x in my_list), ']') prints my_list to the shell without separating commas.

my_list = [1, 2, 3]

print('[', ' '.join(str(x) for x in my_list), ']')

# Output: [ 1 2 3 ]

• The string.join(iterable) method concatenates the elements in the given iterable.
• The str(object) built-in function converts a given object to its string representation.
• Generator expressions or list comprehensions are concise one-liner ways to create a new iterable based by reusing elements from another iterable.

You can dive deeper into generators in the following video:

Note: Combining the join() method with a generator expression and string concatenation is the recommended approach of choice if you want to convert a list to a string without commas instead of printing it.

Here’s an example:

my_list = [1, 2, 3]

s = '[' + ' '.join(str(x) for x in my_list) + ']'

print(s)

# Output: [ 1 2 3 ]

Method 4: Print NumPy Array

Sometimes it is sufficient to use the NumPy default output that is without separating commas. For example, if you print a list it yields [1, 2, 3]. And if you print an array it yields [1 2 3]. You can easily convert a list to a NumPy array using the np.array(lst) constructor.

import numpy as np my_list = [1, 2, 3]

print(np.array(my_list))

# Output: [1 2 3]

Recommended Tutorial: How to Install NumPy?

Where to Go From Here?

Enough theory. Let’s get some practice!

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To become more successful in coding, solve more real problems for real people. That’s how you polish the skills you really need in practice. After all, what’s the use of learning theory that nobody ever needs?

You build high-value coding skills by working on practical coding projects!

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If your answer is YES!, consider becoming a Python freelance developer! It’s the best way of approaching the task of improving your Python skills—even if you are a complete beginner.

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Programmer Humor

Question: How did the programmer die in the shower? ☠

❗ Answer: They read the shampoo bottle instructions:
Lather. Rinse. Repeat.

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