Function transpose::transpose_inplace

pub fn transpose_inplace<T: Copy>(
    buffer: &mut [T], 
    scratch: &mut [T], 
    width: usize, 
    height: usize
)

Transpose the input array in-place.

Given an input array of size input_width * input_height, representing flattened 2D data stored in row-major order, transpose the rows and columns of that input array, in-place.

Despite being in-place, this algorithm requires max(width * height) in scratch space.

// row-major order: the rows of our 2D array are contiguous,
// and the columns are strided
let original_array = vec![ 1, 2, 3,
						   4, 5, 6];
let mut input_array = original_array.clone();
 
// Treat our 6-element array as a 2D 3x2 array, and transpose it to a 2x3 array
// transpose_inplace requires max(width, height) scratch space, which is in this case 3
let mut scratch = vec![0; 3];
transpose::transpose_inplace(&mut input_array, &mut scratch, 3, 2);

// The rows have become the columns, and the columns have become the rows
let expected_array =  vec![ 1, 4,
							2, 5,
							3, 6];
assert_eq!(input_array, expected_array);

// If we transpose it again, we should get our original data back.
transpose::transpose_inplace(&mut input_array, &mut scratch, 2, 3);
assert_eq!(original_array, input_array);

Panics

Panics if input.len() != input_width * input_height or if output.len() != input_width * input_height