Hi,

I have the following array.

[
	[
		[],
		[],
		[[0, 1] [0, 2]],
		[[0, 0] [0, 3]]
	]

	[
		[],
		[],
		[[1, 1] [1, 2]],
		[[1, 0] [1, 3]]
	]
]

and would like it to be arranged like

[
	[
		[[0, 1] [0, 2]],
		[[0, 0] [0, 3]],
		[],
		[]
	]

	[
		[[1, 1] [1, 2]],
		[[1, 0] [1, 3]],
		[],
		[]
	]
]

Any ideas welcome.

NA

> Any ideas welcome.
>
> NA

Use std.algorithm.sort with a custom comparison function.

NA:

> Any ideas welcome.

Is this good enough?

void main() {
    import std.algorithm: swap;

    int[][][][] a =
        [[[],
          [],
          [[0, 1], [0, 2]],
          [[0, 0], [0, 3]]
         ],
         [[],
          [],
          [[1, 1], [1, 2]],
          [[1, 0], [1, 3]]
         ]
        ];

    int[][][][] b =
        [[[[0, 1], [0, 2]],
          [[0, 0], [0, 3]],
          [],
          [],
         ],
         [[[1, 1], [1, 2]],
          [[1, 0], [1, 3]],
          [],
          []
         ]
        ];

    foreach (s1; a) {
        swap(s1[0], s1[2]);
        swap(s1[1], s1[3]);
    }
    assert(a == b);
}


Bye,
bearophile

Tobias Pankrath:

> Use std.algorithm.sort with a custom comparison function.

It's a very nice example of learning algorithms and data fitting. I have shown an answer very fitted (perhaps over-fitted) on the given example. With just the given data there is no way to know how much general the problem is :-)

Bye,
bearophile

On Tuesday, 8 July 2014 at 18:16:55 UTC, bearophile wrote:
> NA:
>
>> Any ideas welcome.
>
> Is this good enough?
>
> void main() {
>     import std.algorithm: swap;
>
>     int[][][][] a =
>         [[[],
>           [],
>           [[0, 1], [0, 2]],
>           [[0, 0], [0, 3]]
>          ],
>          [[],
>           [],
>           [[1, 1], [1, 2]],
>           [[1, 0], [1, 3]]
>          ]
>         ];
>
>     int[][][][] b =
>         [[[[0, 1], [0, 2]],
>           [[0, 0], [0, 3]],
>           [],
>           [],
>          ],
>          [[[1, 1], [1, 2]],
>           [[1, 0], [1, 3]],
>           [],
>           []
>          ]
>         ];
>
>     foreach (s1; a) {
>         swap(s1[0], s1[2]);
>         swap(s1[1], s1[3]);
>     }
>     assert(a == b);
> }
>
>
> Bye,
> bearophile

Thanks but

    int[][][][] a =
        [[[],
          [],
          [],
          [],
          [[0, 1], [0, 2]],
          [[0, 0], [0, 3]]
         ],
         [[],
          [],
          [],
          [],
          [[1, 1], [1, 2]],
          [[1, 0], [1, 3]]
         ]
        ];

will not work and no I can't sort it.

Cheers.

On Tuesday, 8 July 2014 at 18:26:20 UTC, bearophile wrote:
> Tobias Pankrath:
>
>> Use std.algorithm.sort with a custom comparison function.
>
> It's a very nice example of learning algorithms and data fitting. I have shown an answer very fitted (perhaps over-fitted) on the given example.

I had your solution in mind, too, as a hint that the problem might be underspecified.

> With just the given data there is no way to know how much general the problem is :-)

Yeah, but I hope at least he knows it.

NA:

> will not work and no I can't sort it.

Why no sort?


void main() {
    import std.algorithm: sort, SwapStrategy;
    import std.array: empty;

    int[][][][] a =
        [[[],
          [],
          [],
          [],
          [[0, 1], [0, 2]],
          [[0, 0], [0, 3]]
         ],
         [[],
          [],
          [],
          [],
          [[1, 1], [1, 2]],
          [[1, 0], [1, 3]]
         ]
        ];

    int[][][][] b =
        [[[[0, 1], [0, 2]],
          [[0, 0], [0, 3]],
          [],
          [],
          [],
          []
         ],
         [[[1, 1], [1, 2]],
          [[1, 0], [1, 3]],
          [],
          [],
          [],
          []
         ]
        ];

    foreach (s1; a)
        s1.sort!(q{ a.empty < b.empty }, SwapStrategy.stable);
    assert(a == b);
}


Bye,
bearophile

>
> will not work and no I can't sort it.
>
> Cheers.

What are you trying to do? To reorder the elements of a sequence in a specified manner is called sorting, where I live.

On Tuesday, 8 July 2014 at 18:40:37 UTC, bearophile wrote:
> NA:
>
>> will not work and no I can't sort it.
>
> Why no sort?

Thanks,
It works as expected.

As for the sort - wasn't thinking straight.

Cheers,
NA