CODEWITHSUNDEEP
arraysrustslice
arve0
arve0

Reputation: 3647

Is there a short notation for slicing columns from a 2D-array in Rust, using only the standard library?

Is there any notation similar to arr[1..3][3..5] where the first slice 1..3 selects rows, and the second slice 3..5 selects columns?

Example code

fn main() {
    let arr = [[1, 2, 3, 4]; 3];

    let x = arr[0][1];        // first row, second column
    println!("{}", x);        // 2

    let row2d = &arr[0..2];   // slice of two first row, as 2d-array
    println!("{:?}", row2d);  // [[1, 2, 3, 4], [1, 2, 3, 4]]

    let row = &arr[0..2][0];  // slice of first row, as 1d-array, [0] operates on the [0..2] slice
    println!("{:?}", row);    // [1, 2, 3, 4]
                              // wanted first column of two first rows: [[1], [1]]

                              // I can pick a row, then do a slice on the row
    let cols = &arr[0][1..3]; // first row, as 1d-array
    println!("{:?}", cols);   // [2, 3]
}

Link to Rust playground

Upvotes: 1

Views: 2143

Answers (1)

Boiethios
Boiethios

Reputation: 42829

You cannot do that as in, but you can use map to iterate over subslices:

fn main() {
    let arr = [[1, 2, 3, 4]; 3];

    let iter = arr[0..2].iter().map(|s| &s[1..4]);

    for slice in iter {
        for x in slice {
            print!("{} ", x);
        }
        println!();
    }
}

Upvotes: 2

Related Questions