Java-Probability-Collection

Generic and Highly Optimised Java Data-Structure for Retrieving Random Elements with Probability

Usage

ProbabilityCollection<String> collection = new ProbabilityCollection<>();
collection.add("A", 50); // 50 / 85 (total probability) = 0.588 * 100 = 58.8% Chance
collection.add("B", 25); // 25 / 85 (total probability) = 0.294 * 100 = 29.4% Chance
collection.add("C", 10); // 10 / 85 (total probability) = 0.117 * 100 = 11.7% Chance

String random = collection.get();

Proven Probability

The probability test is run 1,000,000 times. Each time getting 100,000 random elements and counting the spread. The test would not pass if the spread had over 1% deviation from the expected probability.

A real world example is provided in ExampleApp.java (within the test folder), Typical Output with 100,000 gets::

   Prob     |  Actual
-----------------------
A: 58.824%  |  58.975% 
B: 29.412%  |  29.256% 
C: 11.765%  |  11.769% 

Performance

Get performance has been significantly improved in comparison to my previous map implementation. This has been achieved with custom compared TreeSets.

Benchmark                                 Mode  Cnt      Score     Error  Units
BenchmarkProbability.collectionAddSingle  avgt    5    501.688 ±  33.925  ns/op
BenchmarkProbability.collectionGet        avgt    5     69.373 ±   2.198  ns/op
BenchmarkProbability.mapAddSingle         avgt    5  25809.712 ± 984.980  ns/op
BenchmarkProbability.mapGet               avgt    5    902.414 ±  22.388  ns/op

Installation

Super Simple: Copy ProbabilityCollection.java into your project

or for the fancy users, you could use Maven:
Repository:

<repository>
    <id>jitpack.io</id>
    <url>https://jitpack.io</url>
</repository>

Dependency:

<dependency>
    <groupId>com.github.lewysDavies</groupId>
    <artifactId>Java-Probability-Collection</artifactId>
    <version>v0.8</version>
</dependency>

Maven Shade This Dependency:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-shade-plugin</artifactId>
  <version>3.1.1</version>
  <executions>
    <execution>
      <configuration>
        <relocations>
           <relocation>
              <!-- Avoid Name Conflics -->
              <pattern>com.lewdev.probabilitylib</pattern>
              <shadedPattern>***<!--YOUR.PACKAGE.HERE-->***.probabilitylib</shadedPattern>
            </relocation>
          </relocations>
       </configuration>
     <phase>package</phase>
     <goals>
       <goal>shade</goal>
     </goals>
   </execution>
  </executions>
</plugin>