Given a n * m matrix (in the type 'a list list), the function val transpose2d = fn : 'a list list -> 'a list list find its transpose and the function val rot90 = fn : 'a list list -> 'a list list rotate it by 90 degrees
in clockwise direction.
- transpose2d([["a","b","c"], ["d","e","f"]]);
val it = [["a","d"],["b","e"],["c","f"]] : string list list
- transpose2d([[1,2,3,4]]);
val it = [[1],[2],[3],[4]] : int list list
- transpose2d([[1.0],[2.0],[3.0],[4.0]]);
val it = [[1.0,2.0,3.0,4.0]] : real list list
- rot90([["a","b","c"], ["d","e","f"]]);
val it = [["d","a"],["e","b"],["f","c"]] : string list list
- rot90([[1,2,3,4]]);
val it = [[1],[2],[3],[4]] : int list list
- rot90([[1.0],[2.0],[3.0],[4.0]]);
val it = [[4.0,3.0,2.0,1.0]] : real list list
To tranpose a matrix, just get the first elements in each row and do that again on the remaining columns.
To rotate a matrix by 90 degrees, we can first tranpose it and reverse each row in the matrix.