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R Loops and Apply Functions

Loops are used to iterate over a sequence of elements, while the apply family of functions provides efficient alternatives to loops for certain operations.

Key Topics

Loops

# Using a for loop
for (i in 1:5) {
    print(i)
}

Output:

[1] 1
[1] 2
[1] 3
[1] 4
[1] 5

Code Explanation: The for loop iterates over the numbers 1 to 5, printing each number.

Apply Functions

The apply() family of functions includes apply(), lapply(), and sapply() for applying functions to elements of arrays, lists, or vectors.

# Using lapply
list_data <- list(a = 1:3, b = 4:6)
result <- lapply(list_data, sum)

print(result)

Output:

$a
[1] 6

$b
[1] 15

Code Explanation: The lapply() function applies the sum function to each element of the list, returning a list of results.

Key Takeaways

  • Use loops for iterating over elements when necessary.
  • The apply() family of functions provides efficient alternatives to loops.
  • lapply() and sapply() are commonly used for list and vector operations.
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