Sorting a list for grid viewing purposes

sort.py

def reorder_list_for_grid(lst, transpose=False, right_to_left=False, bottom_to_top=False, rows=3, cols=3):
    """
    Reorder a list of numbers intended for a grid so that when the grid is filled
    in standard order (left-to-right, top-to-bottom) the numbers appear in the positions
    as if they were filled according to the given instructions.
    
    Parameters:
      lst: list
        The list of numbers to be reordered. Its length must equal rows * cols.
      transpose: bool
        If False, fill rows first then columns. If True, fill columns first then rows.
      right_to_left: bool
        If False, fill left-to-right; if True, fill right-to-left.
      bottom_to_top: bool
        If False, fill top-to-bottom; if True, fill bottom-to-top.
      rows: int, optional
        Number of rows in the grid (default is 3).
      cols: int, optional
        Number of columns in the grid (default is 3).
    
    Returns:
      list: The reordered list.
    """

    # Determine the intended order of cell coordinates based on the flags.
    if not transpose:
        # Outer loop: rows; inner loop: columns.
        row_order = list(range(rows))
        if bottom_to_top:
            row_order = row_order[::-1]  # reverse row order if bottom_to_top flag is True
        col_order = list(range(cols))
        if right_to_left:
            col_order = col_order[::-1]  # reverse column order if right_to_left flag is True
        intended_order = [(r, c) for r in row_order for c in col_order]
    else:
        # Outer loop: columns; inner loop: rows.
        col_order = list(range(cols))
        if right_to_left:
            col_order = col_order[::-1]
        row_order = list(range(rows))
        if bottom_to_top:
            row_order = row_order[::-1]
        intended_order = [(r, c) for c in col_order for r in row_order]

    # Create a mapping from grid coordinate to the number that should go there.
    grid_mapping = {}
    for index, coord in enumerate(intended_order):
        grid_mapping[coord] = lst[index]

    # print("Grid mapping: {}".format(grid_mapping))
    
    # Build the sorted list by reading the grid in standard order (row-major).
    standard_order = [(r, c) for r in range(rows) for c in range(cols)]
    sorted_list = [grid_mapping[coord] for coord in standard_order]
    
    return sorted_list