How do I interleave two Rust vectors by chunks of threes into a new vector?

I need an idiomatic way to interlace these two vectors:

let v1 = vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0];
let v2 = vec![7.0, 8.0, 9.0, 10.0, 11.0, 12.0];

The output I expect is:

[1.0, 2.0, 3.0,
 7.0, 8.0, 9.0,
 4.0, 5.0, 6.0,
 10.0, 11.0, 12.0];

I used itertools chunks method, but I don't believe this is the best implementation because there are two collect calls.

let output = interleave(&v1.into_iter().chunks(3), &v2.into_iter().chunks(3)).map(|v| {v.into_iter().collect::<Vec<f32>>()}).flatten().collect::<Vec<f32>>();

Is there a better way to write this iterator using itertools?

You want Iterator::flatten:

use itertools::interleave;

fn main() {
    let v1 = vec![1.0, 2.0, 3.0, 4.0, 5.0, 6.0];
    let v2 = vec![7.0, 8.0, 9.0, 10.0, 11.0, 12.0];
    let v = interleave(v1.chunks(3), v2.chunks(3))
        .flatten()
        .collect::<Vec<_>>();
    dbg!(v);
}