Re: how to get top N distinct elements from range?

[Chris Cain]

On Friday, 8 March 2013 at 18:17:22 UTC, bearophile wrote:
Otherwise return an impure take of a filter closure from a 
function that keeps the set. Something like (untested):

It seems to work:



import std.stdio, std.range, std.algorithm, std.traits;

auto firstDistinct(Range)(Range r, in size_t n) {
    bool[ForeachType!Range] mySet;

    return r.filter!((k) {
        if (k in mySet)
            return false;
        mySet[k] = true;
        return true;
    }).take(n);
}


I have to say, that's a great example of beautiful simplicity in 
programming. Bravo.