45 lines
2.0 KiB
Rust
45 lines
2.0 KiB
Rust
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//! Utility for transposing multi-dimensional data stored as a flat slice
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//!
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//! This library treats Rust slices as flattened row-major 2D arrays, and provides functions to transpose these 2D arrays, so that the row data becomes the column data, and vice versa.
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//! ```
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//! // Create a 2D array in row-major order: the rows of our 2D array are contiguous,
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//! // and the columns are strided
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//! let input_array = vec![ 1, 2, 3,
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//! 4, 5, 6];
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//!
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//! // Treat our 6-element array as a 2D 3x2 array, and transpose it to a 2x3 array
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//! let mut output_array = vec![0; 6];
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//! transpose::transpose(&input_array, &mut output_array, 3, 2);
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//!
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//! // The rows have become the columns, and the columns have become the rows
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//! let expected_array = vec![ 1, 4,
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//! 2, 5,
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//! 3, 6];
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//! assert_eq!(output_array, expected_array);
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//!
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//! // If we transpose our data again, we should get our original data back.
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//! let mut final_array = vec![0; 6];
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//! transpose::transpose(&output_array, &mut final_array, 2, 3);
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//! assert_eq!(final_array, input_array);
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//! ```
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//!
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//! This library supports both in-place and out-of-place transposes. The out-of-place
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//! transpose is much, much faster than the in-place transpose -- the in-place transpose should
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//! only be used in situations where the system doesn't have enough memory to do an out-of-place transpose.
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//!
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//! The out-of-place transpose uses one out of three different algorithms depending on the length of the input array.
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//!
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//! - Small: simple iteration over the array.
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//! - Medium: divide the array into tiles of fixed size, and process each tile separately.
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//! - Large: recursively split the array into smaller parts until each part is of a good size for the tiling algorithm, and then transpose each part.
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#![no_std]
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extern crate num_integer;
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extern crate strength_reduce;
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mod in_place;
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mod out_of_place;
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pub use in_place::transpose_inplace;
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pub use out_of_place::transpose;
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