R Program to Replace Substring in a String

Introduction

Replacing a substring within a string is a common operation in text processing, allowing you to modify text data efficiently. In R, you can replace substrings using the gsub() function. This guide will walk you through writing an R program that replaces a specified substring with another substring within a given string.

Problem Statement

Create an R program that:

• Prompts the user to enter a string.
• Prompts the user to specify the substring to be replaced.
• Prompts the user to specify the replacement substring.
• Replaces the specified substring with the replacement substring.
• Displays the modified string.

Example:

• Input:
  • Original string: "Hello, World!"
  • Substring to replace: "World"
  • Replacement substring: "R"
• Output: Modified string: "Hello, R!"

Solution Steps

1. Prompt the User for Input: Use the readline() function to take the original string, the substring to replace, and the replacement substring as input from the user.
2. Replace the Substring: Use the gsub() function to replace the specified substring with the replacement substring.
3. Display the Modified String: Use the print() function to display the modified string.

R Program

# R Program to Replace Substring in a String # Step 1: Prompt the user to enter the original string original_string <- readline(prompt = "Enter the original string: ") # Step 2: Prompt the user to enter the substring to be replaced substring_to_replace <- readline(prompt = "Enter the substring to replace: ") # Step 3: Prompt the user to enter the replacement substring replacement_substring <- readline(prompt = "Enter the replacement substring: ") # Step 4: Replace the specified substring with the replacement substring modified_string <- gsub(substring_to_replace, replacement_substring, original_string) # Step 5: Display the modified string print(paste("Modified String:", modified_string)) 

Explanation

Step 1: Prompt the User to Enter the Original String

• The readline() function prompts the user to enter the original string, storing the input in the variable original_string.

Step 2: Prompt the User to Enter the Substring to be Replaced

• The readline() function prompts the user to enter the substring that needs to be replaced, storing it in the variable substring_to_replace.

Step 3: Prompt the User to Enter the Replacement Substring

• The readline() function prompts the user to enter the replacement substring, storing it in the variable replacement_substring.

Step 4: Replace the Specified Substring

• The gsub() function is used to replace all occurrences of substring_to_replace with replacement_substring in original_string. The result is stored in the variable modified_string.

Step 5: Display the Modified String

• The print() function is used to display the modified string along with a descriptive message.

Output Example

Example:

Enter the original string: Hello, World! Enter the substring to replace: World Enter the replacement substring: R [1] "Modified String: Hello, R!" 

Conclusion

This R program demonstrates how to replace a substring within a string using the gsub() function. It covers essential operations such as taking user input, replacing a specified substring, and displaying the modified result. Replacing substrings is a fundamental operation in text processing, making this example valuable for anyone learning R programming.