我有一个已排序元素的列表。与最后的元素相比，第一元素应该被优先化。目前，我只是使用org.springframework.transaction.TransactionSystemException: Could not commit JPA transaction; nested exception is javax.persistence.RollbackException: Transaction marked as rollbackOnly
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:526)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:761)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:730)
at org.springframework.test.context.transaction.TransactionContext.endTransaction(TransactionContext.java:128)
at org.springframework.test.context.transaction.TransactionalTestExecutionListener.afterTestMethod(TransactionalTestExecutionListener.java:224)
at org.springframework.test.context.TestContextManager.afterTestMethod(TestContextManager.java:313)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:94)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:254)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:89)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:193)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: javax.persistence.RollbackException: Transaction marked as rollbackOnly
at org.hibernate.jpa.internal.TransactionImpl.commit(TransactionImpl.java:74)
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:517)
... 29 more
2016-03-26 20:53:52.913 INFO 2448 --- [ Thread-3] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@20deea7f: startup date [Sat Mar 26 20:53:44 CET 2016]; root of context hierarchy
2016-03-26 20:53:52.924 INFO 2448 --- [ Thread-3] j.LocalContainerEntityManagerFactoryBean : Closing JPA EntityManagerFactory for persistence unit 'default'
从我的列表中选择项目。
我正在编写的算法在使用不同的概率分布时效率会更高（如上所述）。不幸的是，我不确定如何实现它
答案 0 :(得分：4)
您可以使用geometric distribution。在几何分布中，获得较大数字的概率呈指数下降。您可以通过调整一些参数来调整优先级。
import numpy
pr = 0.5
x = numpy.random.geometric(pr, 1)[0]
在上面的代码段中，x将对应于您在第一次成功之前必须执行的伯努利试验次数，其中成功概率为0.5。
通常，分布将返回某个数字n的概率等于（1-pr）^（n-1）* pr，其中pr是参数，如代码所示。
所以现在你应该使用x-1（因为列表是0索引的并且x＆gt; = 1）作为选择列表中元素的索引，因为较小的值具有更高的概率从分发中出现，我们已成功捕获您的要求：）