On 12/06/12 13:46, Jens Mueller wrote:
Probably I'm not seeing the issue
auto sample3 = randomSample(iota(0, 100), 5, Random(unpredictableSeed));
writeln(sample3);
auto sample4 = randomSample(iota(0, 100), 5, Random(unpredictableSeed));
writeln(sample4);
auto sample5 = randomSample(iota(0, 100), 5, Random(unpredictableSeed));
writeln(sample5);
outputs
[21, 38, 57, 86, 90]
[21, 39, 68, 79, 94]
[21, 22, 57, 86, 92]
Yes, because you're passing it each time a new RNG seeded with an unpredictable
seed :-)
Try instead
auto rng = Random(unpredictableSeed)
auto sample3 = randomSample(iota(0, 100), 5, rng);
writeln(sample3);
auto sample4 = randomSample(iota(0, 100), 5, rng);
writeln(sample4);
auto sample5 = randomSample(iota(0, 100), 5, rng);
writeln(sample5);
... and you'll get out each time the same values. (Or instead of a
newly-defined generator you could just use rndGen as in my code examples.)
Besides the fact that the ranges always contain 21 (a bug?) this looks
fine to me, doesn't it?
The first-sample-point issue is a bug which I fixed in a recent pull request:
https://github.com/D-Programming-Language/phobos/pull/553#issuecomment-5608813
