Loop over a vector
Last, but not least, in our discussion of loops is the for loop. When you know how many times you want to repeat an action, a for loop is a good option. The idea of the for loop is that you are stepping through a sequence, one at a time, and performing an action at each step along the way. That sequence is commonly a vector of numbers (such as the sequence from 1:10), but could also be numbers that are not in any order like c(2, 5, 4, 6), or even a sequence of characters!
for (value in sequence) {
code
}
In words this is saying, "for each value in my sequence, run this code." Examples could be, "for each row of my data frame, print column 1", or "for each word in my sentence, check if that word is DataCamp."
Let's try an example! First, you will create a loop that prints out the values in a sequence from 1 to 10. Then, you will modify that loop to also sum the values from 1 to 10, where at each iteration the next value in the sequence is added to the running sum.
A vector seq and a variable sum have been defined for you.
This is a part of the course
“Intermediate R for Finance”
Exercise instructions
- Fill in the for loop, using
seqas your sequence. Print outvalueduring each iteration. - Use the loop to sum the numbers in
seq. Each iteration,valueshould be added tosum, thensumis printed out.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Sequence
seq <- c(1:10)
# Print loop
for (value in ___) {
print(___)
}
# A sum variable
sum <- 0
# Sum loop
for (value in seq) {
sum <- ___ + ___
print(___)
}This exercise is part of the course
Intermediate R for Finance
Learn about how dates work in R, and explore the world of if statements, loops, and functions using financial examples.
Loops can be useful for doing the same operation to each element of your data structure. In this chapter you will learn all about repeat, while, and for loops!
Exercise 1: Repeat loopsExercise 2: Repeat, repeat, repeatExercise 3: When to break?Exercise 4: While loopsExercise 5: While with a printExercise 6: While with a plotExercise 7: Break itExercise 8: For loopsExercise 9: Loop over a vectorExercise 10: Loop over data frame rowsExercise 11: Loop over matrix elementsExercise 12: Break and nextWhat is DataCamp?
Learn the data skills you need online at your own pace—from non-coding essentials to data science and machine learning.