I have a range of ranges and need to change it so the elements are column-aligned instead of row-aligned.

For example,
[[1, 2, 3],
 [4, 5, 6],
 [7, 8, 9]]
would change into
[[1, 4, 7],
 [2, 5, 8],
 [3, 6, 0]].

Can I even do this with ranges, and if so, how?

On Saturday, 4 July 2015 at 15:28:56 UTC, Tanel Tagaväli wrote:
> I have a range of ranges and need to change it so the elements are column-aligned instead of row-aligned.
>
> For example,
> [[1, 2, 3],
>  [4, 5, 6],
>  [7, 8, 9]]
> would change into
> [[1, 4, 7],
>  [2, 5, 8],
>  [3, 6, 0]].
>
> Can I even do this with ranges, and if so, how?

Try std.range.transposed:
http://dlang.org/phobos/std_range.html#.transposed

On Saturday, 4 July 2015 at 16:29:44 UTC, Marc Schütz wrote:
> Try std.range.transposed:
> http://dlang.org/phobos/std_range.html#.transposed

Does this work with user-defined types?

I defined two structs that implement the InputRange(possibly ForwardRange) interface, an integer range and a range of those integer ranges.

DMD tells me the "transposed" template cannot deduce function from the arguments, which is a range of integer ranges.
The template does, however, work on a two-dimensional array.

The "save" method is implemented using a simple "return this", could this be to blame?

On Sunday, 5 July 2015 at 00:18:18 UTC, Tanel Tagaväli wrote:
> On Saturday, 4 July 2015 at 16:29:44 UTC, Marc Schütz wrote:
>> Try std.range.transposed:
>> http://dlang.org/phobos/std_range.html#.transposed
>
> Does this work with user-defined types?
>
> I defined two structs that implement the InputRange(possibly ForwardRange) interface, an integer range and a range of those integer ranges.
>
> DMD tells me the "transposed" template cannot deduce function from the arguments, which is a range of integer ranges.
> The template does, however, work on a two-dimensional array.
>
> The "save" method is implemented using a simple "return this", could this be to blame?

This should be fine. Which of the ranges is the ForwardRange? It should be the range-of-ranges.

You can check which of the template constraints fails:

import std.range;
alias RangeOfRanges = typeof(myRangeOfRanges);
pragma(msg, isForwardRange!RangeOfRanges);
pragma(msg, isInputRange!(ElementType!RangeOfRanges));
pragma(msg, hasAssignableElements!RangeOfRanges);

Maybe it's the last condition, `hasAssignableElements`. I don't know whether that one is really necessary...

On Sunday, 5 July 2015 at 11:35:14 UTC, Marc Schütz wrote:
> Maybe it's the last condition, `hasAssignableElements`. I don't know whether that one is really necessary...

It probably is. The last check returned false.
Since I already would have to implement "r.front = ", I'll just use arrays.

Thanks for the help.