How can I convert a list into a list of tuples?

I've got a list of elements: [1, 2, 3, 4, 5, 6]. I want to convert it into [(1, 2), (3, 4), (5, 6)].
How can I achieve this?

To convert the given list into the format given use this :

fn main() {
    let original_list = vec![1, 2, 3, 4, 5, 6];
    
    let result_list: Vec<(i32, i32)> = original_list
        .chunks(2)
        .filter(|chunk| chunk.len() == 2)
        .map(|chunk| (chunk[0], chunk[1]))
        .collect();

    println!("{:?}", result_list); // [(1, 2), (3, 4), (5, 6)]
}

However do note that the code above will require a even number of elements in the list , else the 'extra' element will be ignored

Here is a solution that does not depend on chunks

fn main() {
let arr = vec![1, 2, 3, 4, 5, 6,7];
let out : Vec<_> = 
   (1..arr.len()).step_by(2).map(|i|  {
     (arr[i-1], arr[i])
}).collect();
println!("{:?}", out);
}

However whats the difference , as both output the same thing (even with odd numbers)

There's no functional difference but indexing in a loop is less idiomatic, since it incurs extra runtime checks and makes the code more complex for no benefit (given that there's now iterators and indexing).

However, I'd just use chunks_exact instead.

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Thanks for clarifying the reason , between the 2 methods. I didn't even know the chunk_exact method even existed. Looks like rust has tons of unknown yet really useful functions built-in in the standard library

1 Like

The most direct way is https://docs.rs/itertools/latest/itertools/trait.Itertools.html#method.tuples from the itertools crate, which turns an iterator of T into an iterator of tuples of T.

5 Likes

I was under the impression chunks was not stable rust. I stand corrected.

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