Re: Finding the index of the maximum value in an associative array

[John Colvin via Digitalmars-d-learn]

On Tuesday, 30 May 2017 at 18:05:07 UTC, H. S. Teoh wrote:

On Tue, May 30, 2017 at 05:57:04PM +0000, Lyle via Digitalmars-d-learn wrote:

Hi,

I have an associative array of type int[ulong] and I'm trying to get the index of the maximum value, like this:

int[ulong] aa = [1UL: 2000,
                 2UL: 5000,
                 5UL: 1000];

writeln(aa.maxIndex); // should print 2

Can anyone help me out?

[...]

Try this:

        void main() {
                import std.algorithm.iteration : fold;
                import std.array : byPair;
                import std.stdio : writeln;

                int[ulong] aa = [1UL: 2000,
                                2UL: 5000,
                                5UL: 1000];

                writeln(aa.byPair
                          .fold!((a,b) => a[1] < b[1] ? b : a)[0]);
        }

writeln(aa.byPair.maxElement!(p => p[1])[0]);

or with https://github.com/dlang/phobos/pull/5436 :

writeln(aa.byPair.maxElement!(p => p.value).key);