What is String Slicing in Python?

Introduction

Hey Ninjas!! Welcome to another article on Python. Strings are immutable data types in Python. We cannot update the string's value. Slicing strings create a substring from the original string. Do you know we can easily slice the letters of the string? Today we will learn about String Slicing in Python. We will also look into details of the methods of String Slicing in Python.

The article explains the details of string slicing in Python. Let's get started.

Slicing a String

Slicing means extracting a part from something, and slicing a string means extracting some part from a string. This extracted part is also referred to as a sub-string. In short, string slicing in Python is obtaining a substring from a larger string by slicing it based on specific criteria. String slicing allows us to obtain a specific range of characters from a string based on their respective indices.

How String Slicing in Python works?

String slicing in Python allows you to extract a portion of a string by specifying a start and end index. It follows the format string[start:end], where start is the index where slicing begins (inclusive) and end is the index where it ends (exclusive).

For example, with the string my_string = "Hello, World!", if you use my_string[7:12], it will return "World".

If you omit start, it starts from the beginning of the string. If you omit end, it goes to the end of the string.

Negative indices are also valid. string[-1] refers to the last character, string[-2] refers to the second last, and so on.

Why is Python String Slicing Useful? 

Python string slicing is advantageous for a number of factors:

• Subsetting Data: It makes it simple to access and manipulate substrings inside a bigger text since it enables you to extract specific chunks of a string
• Data Extraction: It makes the process of sifting through strings to find relevant information and extracting it, which is essential for tasks like data cleaning and analysis, simpler
• String Manipulation: Slicing makes it easier to manipulate strings in a variety of ways, including reversing strings and extracting words or characters for additional use
• Efficient Access: Slicing offers direct access to a segment rather than iterating through a string character by character, which may be more effective for some jobs
• Substring Creation: It permits the creation of substrings for activities like producing distinctive IDs, decoding file paths, or producing outputs with specific formatting
   

Methods of String Slicing in Python

String slicing in Python can be performed using two methods:

1. Slice() Method
2. List Slicing / Array Slicing
    

Let's look into the details of each of them.

Slice() Method

The slice() method returns an object containing the range of string slicing. The parameter includes a set of range of values defined as (start, stop, step). Let's look at the syntax of the slice method().

Syntax:

slice( Start_Index, End_Index, Steps )

Here, Start_Index is the starting index of the string. End_Index is the last index before which all elements are considered. Steps are the number of steps to be jumped in each iteration. The Start_Index and Steps are optional. The Start_Index is 0 by default. The step is 1 by default.

Slice() Method Examples

Example - 1

When only one parameter is passed to the slice() method, it takes it as the end index.

Code:

string = 'Coding Ninjas'
print(string[slice(6)])

Output:

Coding

Explanation:

The slice(6) method slices the string from starting to index 6 (excluding) and prints the result.

Example - 2

You can slice strings within a given range. Have a look at the following example:

Code:

string = 'Coding Ninjas'
print(string[slice(2,10)])

Output:

ding Nin

Explanation:

The slice(2,10) method slices the string from index 2 to index 9 and prints the result.

Example - 3

String Slicing in Python can be performed within a given range by skipping the values.

Code:

string = 'Coding Ninjas'
print(string[slice(2,10,3)])

Output:

dgi

Explanation:

The slice(2,10,3) method slices the string from index 2 to index 9 and prints every 3rd letter.

Example - 4

The String Slicing in Python can also be performed on backward indexing.

Code:

string = 'Coding Ninjas'
print(string[slice(-10,-3)])

Output:

ing Nin

Explanation:

The above code snippet uses backward indexing. The slice(-10,-3) method slices the string from index -10 to index -4 and prints them.

List Slicing / Array Slicing

The List Slicing method is the most common way of string slicing in Python. The parameter includes a set of range of values defined as [start, stop, step]. Let's look at the syntax:

Syntax:

string[ Start_Index : End_Index : Steps ] 

Here, Start_Index is the starting index of the string. End_Index is the last index before which all elements are considered. The step is the number of steps to be jumped in each iteration. Let's look at a few examples to understand string slicing in python.

List Slicing / Array Slicing Examples

Example - 1

Slicing a string within a given range

Code:

string = 'Coding Ninjas'
print(string[7:12])

Output:

Ninja

Explanation:

The above code snippet prints the letters from index 7 to index 11.

Example - 2

You can slice the string within a given range by skipping the letters. 

Code:

string = 'Coding Ninjas'
print(string[1:12:2])

Output:

oigNna

Explanation:

The above code snippet prints every 2nd letter from index 1 to index 11.

Example - 3

When the starting index is not given, it takes 0 as the starting index.

Code:

string = 'Coding Ninjas'
print(string[:7])

Output:

Coding 

Explanation:

The above code snippet prints the letters from index 0 to index 6.

Example - 4

When the end index is not provided, it takes the last index as the end index.

Code:

string = 'Coding Ninjas'
print(string[4:])

Output:

ng Ninjas

Explanation:

The above code snippet prints the letters from index 4 to the last index.

Frequently Asked Questions

What is string slicing in Python?

In Python, string slicing refers to the extraction of a portion of a string from the bigger string, also known as a sub-string. String slicing is an efficient method in Python to manipulate a string to extract and process specific text from the data.

What is Python list slicing?

In Python, list slicing is a common string slicing method. It is a technique to extract some specific data portion from a string. It is a flexible method to manipulate the data based on specific requirements.

How can you skip letters in slicing strings?

In Python, you can skip letters in string slicing by specifying the step parameter in slice notations. You need to pass the step parameter along with starting index and end index to skip letters in slicing strings.

Conclusion

In this article, we have extensively discussed the details of String Slicing in Python and Methods of String Slicing in Python. We hope that the blog has helped you enhance your knowledge regarding this topic.

Recommended Readings:

• Encapsulation in Python
• Switch Case in Python
• Binary Search Python
• Literals in Python
   

Happy Coding!!