On 10/06/2018 01:07 PM, bauss wrote:

> uniq will not work with, say a class and the class will require you to
> implement opCmp, which you can't always do for classes you don't have
> access to.

Remembering that uniq works with a custom predicate, which should be sufficient in most of those case.

> to use ..sort
> and it requires opCmp again.

Same for sort: works with a custom predicate.

> Things like .group and .uniq should work without sorted
> ranges. You can't always expect a range to be sorted to perform such
> algorithms.

Yes, it can be inconvenient but I'm under the impression that making algorithmic complexity a property of a function is agreed by most people. (For D, algorithmic complexity is in the documentations of functions; alas, uniq lacks it.) So, it's a good thing that we know that uniq is always O(N).

Ali

On Saturday, 6 October 2018 at 13:17:22 UTC, bauss wrote:
> Let's say you have a range with struct, but some of the struct are duplicates of each other.
>
> Is there a standard function in Phobos to remove duplicates?
>
> My first thought was "uniq", but it can't really do it like that, but it doesn't work.
>
> See: https://run.dlang.io/is/IcFEtw
>
> Is there another function in Phobos that perhaps would work?
>
> I can of course write my own function, but if there is a standard function that can do it, then I'd rather use that.

Unless you want to implement opCmp() and do the .sort.uniq then, you may find this one-liner helpful:

randomAccessRange.fold!((arr, elem) => arr.canFind(elem) ? arr : (arr ~= elem))((ElementType!(typeof(randomAccessRange))[]).init)

Applied in your example: https://run.dlang.io/is/3KjRvY

But yes, it is de facto a custom function. I don't think that there is a function in Phobos that will perfectly deduplicate your range without having it sorted before.