> What could be done is
> 1. create a static method in the distribution class
> 2. have the "sample()" method call that one
+1. I like that the sample implementation for a distribution is in the
actual distribution class.
Denis
On 08/06/2012 02:30 AM, Gilles Sadowski wrote:
[...]
The original code above illustrates the convenience of being able to
just make direct calls to randomData.nextXxx, which is why this
class exists ;)
As I wrote in another post, I'm not against the convenience methods. But
IMO, they should be located in a new "DistributionUtils" class.
Why? RandomData is pretty descriptive and exactly what these
methods do. They generate random data.
Fine...
But can we plan to merge "RandomData" and "RandomDataImpl"?
And we should also find a way to remove the code duplication (in the
distribution's "sample()" method and in the corresponding "next..." method).
+1 - the implementations can be moved. When I last looked
carefully at this, the distribution methods were delegating to impls
in RandomDataImpl. What we have agreed is to move the impls into
the distribution classes for the basic sampling methods. That
should not be too hard to do. I will do that if no one beats me to it.
I did it in r1363604.
What still needs to be done is redirect the "next..." to the "sample()"
method of the appropriate distribution.
But I had already raised the issue of efficiency: each call to e.g.
nextInt(p, q)
will entail the instantiation of a UniformRealDistribution object.
What could be done is
1. create a static method in the distribution class
2. have the "sample()" method call that one
---
public class UniformRealDistribution extends ... {
// ...
public static int nextInt(RandomGenerator rng,
int a,
int b) {
final double u = rng.nextDouble();
return u * b + (1 - u) * a;
}
public int sample() {
// Here "random", "lower" and "upper" are instance variables.
return nextInt(random, lower, upper);
}
}
---
And "nextInt" from "RandomDataImpl" would also be redirected to the static
method in the distribution class:
---
import org.apache.commons.math3.distribution.UniformRealDistribution;
public class RandomDataImpl ... {
// ...
public int nextInt(int lower, int upper) {
return UniformRealDistribution.nextInt(getRan(), lower, upper);
}
}
---
OK?
Gilles
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