Is there a way to get every n * i element of a vector?

Question

Is there any clever way to get every n * i element of a vector? I have this vector:

let example = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];

I want every third value of this vector, so the output will be:

let result = vec![3, 6, 9];

I know that I can achieve this with a for loop:

let mut result: Vec = vec![];
let offset = 3;
for (index, value) in example.iter().enumerate() {
    if (index + 1) % offset == 0 {
        result.push(value.clone());
    }
}

user_2189130 · Answer

To iterate over every nth element, use .step_by(). However, using that starts at the initial value, you'll need to chain .skip() as well. playground:

let example = vec![1, 2, 3, 4, 5, 6, 7, 8, 9];
let n = 3;
let result: Vec<_> = example.iter().skip(n-1).step_by(n).copied().collect();
println!("{:?}", result);

[3, 6, 9]

Is there a way to get every n * i element of a vector?

1 Answers