What is Python String Interpolation?

String interpolation in Python programming language can be defined as the method of inserting data into a placeholder in a string literal (here the term placeholder is defined as a variable to which any value or data can be assigned by the programmer later). It aids in interactively formatting the result in a more visually appealing manner. Python provides several methods for formatting string literals. String methods usually always produce new values but never alter the original string.

For example, let's suppose you have a format for greeting someone that says "Hey Name of the Person, hope you are doing well!" you might want to substitute the placeholder for the individual's name with an actual name. This process is known as string interpolation.

There are four ways in which programmers can use the concept of Python String Interpolation. String interpolation can be accomplished in the following ways:

a. F-Strings

Python 3.6 introduced a new Python string interpolation technique known as the literal string interpolation, as well as a new literal prefix f. This new string formatting method is both potent and simple to use. It allows the programmer to use the concept of embedded Python expressions within string constants.

Let's go through an example to understand the concept of F-Strings in a better way.

Now, on running the program given above:

In the preceding example, the symbolic prefix f instructs Python programming language to reinstate the contents of the two string variables named and programmed within the braces. As a result, when users print, the output produced is shown above.

This new string interpolation is effective because it allows us to embed arbitrary Python expressions and perform inline arithmetic.

b. %-Formatting

In Python, strings have a special built-in operation that can be easily accessed with the % operator. We can easily perform simple string interpolation by making use of the % symbol.

Output:

In the preceding example, we have used 2 %s string format specifiers as well as 2 strings in () brackets, 'Welcome' and 'Hello'. As a result, the output we receive is "Welcome Hello". Programming Language Python makes use of the %s string format specifier to tell it where to replace the value.

If the programmer desires to create numerous substitutions in the same string, and also because the % operator takes only one single argument, we must wrap the right-hand part in a tuple, as demonstrated in the instance below.

c. str.format()

Str.format() is utilized for positional formatting in Python, which enables the programmers to reorder placeholders inside of string literals without altering the order in which the strings are mentioned in .format(). The symbol {} serves only as a placeholder and is the only value taken by a method. In Str.format(), format() will then be modified in the output, but the other string literals which have been used in the program will remain unaltered in the result of printing.

Programmers can accomplish the concept of positional formatting accomplished by inserting a keyword or an index into placeholders. By default, if neither of these is defined by the programmer, then the objects will be infused in the similar order they are listed in .format().

Multiple attributes can also be passed. The parameters passed can be an integer, a precision floating-point value, a character, a string, etc can be used as the value.

Passing a single variable as a parameter:

The output we get on running this particular code is as follows:

Multiple attributes can also be passed. The parameters passed can be an integer, a precision floating-point value, a character, a string, etc can be used as a value. Let's write a program with multiple parameters.

d. Template Strings

Template Strings in the programming language is a type of string interpolation method in Python which is defined as a simpler and less powerful string interpolation process. To utilize it, we must import the Template class from Python's built-in string module.

On running the program, the output we get is as follows:

Advantages of Python String Interpolation

• The concept of String interpolation in the programming language  Python allows us to make better use of print statements. Print statements are likely to be found throughout your script, whether for debugging code or confirming results.
• Makes it very easy to print statements in Python.
• The major benefit of using %-format in Python String Interpolation is that programmers can instantly pass a tuple or list as a parameter. This is very effective if you need to pass a long list of arguments, such as when reading information from a database or worksheet and formatting a long string in XML or JSON format.

Disadvantages of Python String Interpolation

• The method %-format used in String Interpolation is not recommended to programmers since it reduces code readability making it less appealing.

Important Points

• The %-format technique is defined as an old interpolation strategy that is no longer preferred because it reduces code readability.
• Programmers need to pass the desired string object to the format() function to perform string interpolation in the str.format() method as discussed above in the article.
• We create a template in the template method by trying to import the template class from the built-in string module.
• The last type of Python string interpolation method is the Literal String Interpolation which is defined as a powerful interpolation procedure that is simple to operate and improves code readability.

Learn More

Are you new to Python? If yes, you can go through the following article: What is Python? to understand the concepts of Python as well as the features of the programming language.

To know about the various applications of Python in real life, programmers can visit the following article: Applications of Python.

To know in which language Python is written programmers can visit the following article: In which language Python is written?.

To Know more about strings in python check out this article: Python Strings.