[jira] [Work logged] (MATH-1522) The generic parameter of ClusterRanking can move onto method

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MATH-1522?focusedWorklogId=400555&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-400555 ]

ASF GitHub Bot logged work on MATH-1522:
----------------------------------------

                Author: ASF GitHub Bot
            Created on: 10/Mar/20 04:36
            Start Date: 10/Mar/20 04:36
    Worklog Time Spent: 10m 
      Work Description: chentao106 commented on pull request #124: MATH-1522 Remove generic parameter in ClusterEvaluator and ClusterRan…
URL: https://github.com/apache/commons-math/pull/124
 
 
   MATH-1522 Remove generic parameter in ClusterEvaluator and ClusterRanking, then the object declarations can be easier, and can be reused.
   
   Before remove the generic parameter:
   ```java
   ClusterRanking<DoublePoint> evaluator = new SumOfClusterVariances<>();
   List<Cluster<DoublePoint>> clusters1 = ...
   evaluator.compute(clusters1); // It is OK.
   ...
   // The evaluator could be reused, but trigger a compile error
   List<Cluster<MyClusterable>> clusters2 = ...
   evaluator.compute(clusters2); // Compile error
   ```
   
   After remove the generic parameter:
   ```java
   // The variable define is simple now.
   ClusterRanking evaluator = new SumOfClusterVariances();
   ...
   List<Cluster<DoublePoint>> clusters1 = ...
   double score1 = evaluator.compute(clusters1); // OK.
   ...
   // It can be reused now.
   List<Cluster<MyClusterable>> clusters2 = ...
   double score2 = evaluator.compute(clusters2); // OK.
   ```
 
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Issue Time Tracking
-------------------

            Worklog Id:     (was: 400555)
    Remaining Estimate: 0h
            Time Spent: 10m

> The generic parameter of ClusterRanking can move onto method
> ------------------------------------------------------------
>
>                 Key: MATH-1522
>                 URL: https://issues.apache.org/jira/browse/MATH-1522
>             Project: Commons Math
>          Issue Type: Improvement
>            Reporter: Chen Tao
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> The generic parameter on class "ClusterRanking" is unnecessary, 
> it is redundancy when define a variable, and hard to reuse(it could be):
> {code:java}
> ClusterRanking<DoublePoint> evaluator = new SumOfClusterVariances<>();
> List<Cluster<DoublePoint>> clusters1 = ...
> evaluator.compute(clusters1); // It is OK.
> ...
> // It could be reused globally, but now trigger a compile error
> List<Cluster<MyClusterable>> clusters2 = ...
> evaluator.compute(clusters2); // Compile error
> {code}
> The generic parameter of ClusterRanking can be move onto method: 
> {code:java}
> @FunctionalInterface
> public interface ClusterRanking {
>     /**
>      * Computes the rank (higher is better).
>      *
>      * @param clusters Clusters to be evaluated.
>      * @return the rank of the provided {@code clusters}.
>      */
>     <T extends Clusterable> double compute(List<? extends Cluster<T>> clusters);
> }
> {code}
> Then we can define a ClusterRanking easier and reuse it globally:
> {code:java}
> // The variable define is simple now.
> ClusterRanking evaluator = new SumOfClusterVariances();
> ...
> List<Cluster<DoublePoint>> clusters1 = ...
> double score1 = evaluator.compute(clusters1); // OK.
> ...
> // It can be reused globally now.
> List<Cluster<MyClusterable>> clusters2 = ...
> double score2 = evaluator.compute(clusters2); // OK.
> {code}



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