Loops in R Programming

Introduction

Loops are used to execute a block of code repeatedly. In R, there are three main types of loops: for, while, and repeat. This tutorial provides examples for each type of loop.

1. for Loop

The for loop iterates over a sequence (e.g., vector, list) and executes the code block for each element.

Syntax:

    for (variable in sequence) {
      # Code to execute
    }

Example:

    # Print numbers from 1 to 5
    for (i in 1:5) {
      print(i)
    }

2. while Loop

The while loop executes a block of code as long as the condition is TRUE.

Syntax:

    while (condition) {
      # Code to execute
    }

Example:

    # Print numbers from 1 to 5
    x <- 1
    while (x <= 5) {
      print(x)
      x <- x + 1
    }

3. repeat Loop

The repeat loop executes a block of code indefinitely until explicitly exited using the break statement.

Syntax:

    repeat {
      # Code to execute
      if (condition) {
        break
      }
    }

Example:

    # Print numbers from 1 to 5
    x <- 1
    repeat {
      print(x)
      x <- x + 1
      if (x > 5) {
        break
      }
    }

4. Nested Loops

Loops can be nested inside each other to perform more complex operations.

Example:

    # Print a multiplication table
    for (i in 1:3) {
      for (j in 1:3) {
        print(paste(i, "x", j, "=", i * j))
      }
    }

5. Using next and break

The next statement skips the current iteration, and the break statement exits the loop.

Example:

    # Skip even numbers and stop at 7
    for (i in 1:10) {
      if (i %% 2 == 0) {
        next
      }
      if (i > 7) {
        break
      }
      print(i)
    }

Conclusion

Loops are essential for automating repetitive tasks in R. Depending on the use case, you can choose for, while, or repeat loops to handle different scenarios effectively.




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