Rust extendr/rextendr code to transpose R's character matrix

lib.rs

use extendr_api::prelude::*;

#[extendr]
fn transpose_char_matrix(matrix: RMatrix<Rstr>) -> Robj {
    // Take the input dimensions
    let dims = matrix.dim();

    // Get the number of rows and columns
    let nrows = dims[0] as usize;
    let ncols = dims[1] as usize;

    // Create a new vector to hold the transposed data
    let mut transposed_data = Vec::with_capacity(nrows * ncols);

    // Transpose the matrix by swapping rows and columns
    for row in 0..nrows {
        for col in 0..ncols {
            // Get a reference to the element at position (row, col)
            let value = &matrix[[row, col]];
            // Collect the reference for the transposed matrix
            transposed_data.push(value);
        }
    }

    // Create a Strings vector from the transposed data
    let str_vec = Strings::from_values(transposed_data);

    // Create the dimension vector
    let dim = [ncols as i32, nrows as i32];

    // Set the dimensions attribute
    let mut robj = str_vec.into_robj();
    let _ = robj.set_attrib("dim", Robj::from(&dim));

    // Return the transposed matrix as an R object
    robj
}

extendr_module! {
    mod myextendr;
    fn transpose_char_matrix;
}

> aaa
     [,1]      [,2]    
[1,] "efffasw" "fdxfj" 
[2,] "wqweqe"  "yjjyjy"
[3,] NA        "rweaa" 

> t(aaa)
     [,1]      [,2]     [,3]   
[1,] "efffasw" "wqweqe" NA     
[2,] "fdxfj"   "yjjyjy" "rweaa"

> transpose_char_matrix(aaa)
     [,1]      [,2]     [,3]   
[1,] "efffasw" "wqweqe" NA     
[2,] "fdxfj"   "yjjyjy" "rweaa"