Python .join()

In Python, the .join() method concatenates all items from an iterable into a single string. It’s especially useful when there is a need to combine multiple string elements with a specific separator, like commas, spaces, or newlines.

Syntax

The .join() method is called on a separator string:

string.join(iterable)

Parameters:

• The separator can be any string, even an empty one, and is placed between each element from the iterable.
• The iterable is any object that can be iterated over like tuples or lists. All values of the iterable must be strings.

Return value:

The .join() method returns a new string containing the concatenated result.

Example 1: Joining a List of Words with Space

This example joins the elements of the fruits list with a single space (" ") in between:

fruits = ["Apples", "Bananas", "Blueberries"]

combined = " ".join(fruits)

print(combined)

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Here is the output:

Apples Bananas Blueberries

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Example 2: Using a Hyphen as Separator

This example uses .join() to append elements of a tuple with a hyphen ("-") as separator:

vehicles = ("bicycle", "car", "moped", "truck")

joined = "-".join(vehicles)

print(joined)

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Here is the output:

bicycle-car-moped-truck

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Codebyte Example: Joining Characters in a String

In this example, the string "hello" is treated as an iterable of characters, which are joined using "." as a separator:

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Here is the output:

h.e.l.l.o

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Frequently Asked Questions

1. Can I use .join() with numbers?

No, all elements must be strings. If you try to join a list of integers using .join(), you’ll get a TypeError. Use str() or a list comprehension to convert them first:

numbers = [1, 2, 3]

joined = "-".join(str(num) for num in numbers)

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2. What happens if the list passed to .join() is empty?

If the iterable is empty, .join() returns an empty string:

print(",".join([])) # Output: ''

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3. Is .join() faster than using + in a loop?

Yes. Using .join() is much faster and more memory-efficient than concatenating strings with + in a loop. It’s the recommended way to concatenate many strings.