range result in Tuple! and how to convert into assocArray by sort?

[Ali Çehreli]

On 5/9/22 20:38, rikki cattermole wrote:

 > this is a super expensive
 > method for doing something pretty simple.

Yes! :)

Assuming the data is indeed validated in some way, the following should 
be even faster. It validates the data after the fact:

import std.stdio;
import std.range;
import std.exception;
import std.algorithm;
import std.format;

const ulong[] alphabet = [ 'A', 'C', 'G', 'T' ];

void main() {
   string s = "ACGTACGT";

   auto counts = new ulong[char.max];

   foreach(char c; s) {
     counts[c]++;
   }

   validateCounts(counts);
   writeln(counts.indexed(alphabet));
}

void validateCounts(ulong[] counts) {
   // The other elements should all be zero.
   enforce(counts
           .enumerate
           .filter!(t => !alphabet.canFind(t.index))
           .map!(t => t.value)
           .sum == 0,
           format!"There were illegal letters in the data: %s"(counts));
}

Ali