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From "Zhong Yanghong (JIRA)" <j...@apache.org>
Subject [jira] [Created] (KYLIN-3306) Fix the rarely happened unit test exception of generic algorithm
Date Wed, 21 Mar 2018 05:39:00 GMT
Zhong Yanghong created KYLIN-3306:
-------------------------------------

             Summary: Fix the rarely happened unit test exception of generic algorithm
                 Key: KYLIN-3306
                 URL: https://issues.apache.org/jira/browse/KYLIN-3306
             Project: Kylin
          Issue Type: Bug
            Reporter: Zhong Yanghong
            Assignee: Zhong Yanghong


There's a bug in the following code:
{code}
private Chromosome rouletteWheel(final List<Chromosome> chromosomes, final double totalFitness)
{
        float rnd = (float) (GeneticAlgorithm.getRandomGenerator().nextDouble() * totalFitness);
        float runningScore = 0;
        for (Chromosome o : chromosomes) {
            if (rnd >= runningScore && rnd <= runningScore + o.getFitness())
{
                return o;
            }
            runningScore += o.getFitness();
        }
        return null;
    }
{code}

We should use double instead of float.

For example, (float) (0.9999999988948809 * 40.510999999999996) = 40.511 > 40.510999999999996



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