Simplify walk for upscaling grid
Simplify walk for upscaling grid

Just walk the grid and emit the same positions multiple times, instead
of calculating the same positions over and over again.

    >>> grid = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
    >>> scale = 2

As list instead of a generator, to illustrate the nested comprehension:

    >>> pprint.pprint(
    ...     [[pix for pix in row for _ in range(scale)]
    ...      for row in grid for _ in range(scale)]
    ... )
    [[1, 1, 2, 2, 3, 3],
     [1, 1, 2, 2, 3, 3],
     [4, 4, 5, 5, 6, 6],
     [4, 4, 5, 5, 6, 6],
     [7, 7, 8, 8, 9, 9],
     [7, 7, 8, 8, 9, 9]]

knorrie/btrfs-heatmap