GFact | Most efficient way to Concatenate Strings in Python

Concatenation is an operation that is very frequently used in various problems related to strings. There are multiple methods to concat strings in various languages. Python is also such a language that supports various string concatenation methods. But have you ever wondered which one is the most efficient? If your answer is “YES” then the following post will be helpful to you because in this post we will discuss the most efficient way to Concatenate Strings in Python language.

Which is the most efficient way to Concatenate Strings in Python?

Among all the methods of String concatenation, join() is the most efficient way to Concatenate Strings in Python.

What are some other methods of concatenation of Strings in Python?

• Using + operator
• Using join() method
• Using % operator
• Using format() function
• Using “,” (comma)

Why is join() method most efficient method for String concatenation?

join() method creates a single string object, whereas using the + operator creates a new string object every time it is called.

So, we can say, the join() method is the most efficient way to concatenate strings in Python.

How to use the join() method ?

In this example, we have a list of strings called words. We want to join these strings together into a sentence, so we use the join() method. We pass the list of strings to the method, and we also pass a separator string, which in this case is a space. The join() method then combines all of the strings in the list with the separator string, resulting in a final sentence.

1. Joining a list of numbers as strings

Python3

numbers = [1, 2, 3, 4, 5]
numbers_as_strings = [str(num) for num in numbers]
result = "-".join(numbers_as_strings)
print(result)

Output

1-2-3-4-5

2. Joining a list of sentences into a paragraph

Python3

sentences = ["This is the first sentence.",
             "This is the second sentence.", "This is the third sentence."]
paragraph = "\n".join(sentences)
print(paragraph)

Output

This is the first sentence.
This is the second sentence.
This is the third sentence.

3. Joining a list of words into a URL path

Python3

words = ["blog", "python", "efficient", "string", "concatenation"]
path = "/".join(words)
url = "https://www.example.com/" + path
print(url)

Output

https://www.example.com/blog/python/efficient/string/concatenation

4. Joining a list of strings using a custom separator function

Python3

strings = ["foo", "bar", "baz", "qux", "quux"]


def separator_func(index):
    return "-" if index % 2 == 0 else "_"


result = "".join([string + separator_func(i)
                  for i, string in enumerate(strings)])
print(result)

Output

foo-bar_baz-qux_quux-

5. Joining a list of strings using a prefix and suffix

Python3

words = ["apple", "banana", "orange"]
prefix = "I like to eat "
suffix = "s for breakfast."
result = ", ".join([prefix + word + suffix for word in words])
print(result)

Output

I like to eat apples for breakfast., I like to eat bananas for breakfast., I like to eat oranges for breakfast.

6. Joining a list of characters using a custom separator

Python3

chars = ["a", "b", "c", "d", "e", "f"]
separator = " "
result = separator.join(chars[i] + chars[i+1]
                        for i in range(0, len(chars)-1, 2))
print(result)

Output

ab cd ef