我使用ALS预测评级,这是我的代码:为什么Spark ML ALS算法打印RMSE = NaN?
val als = new ALS()
.setMaxIter(5)
.setRegParam(0.01)
.setUserCol("user_id")
.setItemCol("business_id")
.setRatingCol("stars")
val model = als.fit(training)
// Evaluate the model by computing the RMSE on the test data
val predictions = model.transform(testing)
predictions.sort("user_id").show(1000)
val evaluator = new RegressionEvaluator()
.setMetricName("rmse")
.setLabelCol("stars")
.setPredictionCol("prediction")
val rmse = evaluator.evaluate(predictions)
println(s"Root-mean-square error = $rmse")
但得到一些负面的分数和RMSE是楠:
+-------+-----------+---------+------------+
|user_id|business_id| stars| prediction|
+-------+-----------+---------+------------+
| 0| 2175| 4.0| 4.0388923|
| 0| 5753| 3.0| 2.6875196|
| 0| 9199| 4.0| 4.1753435|
| 0| 16416| 2.0| -2.710618|
| 0| 6063| 3.0| NaN|
| 0| 23076| 2.0| -0.8930751|
Root-mean-square error = NaN
如何取得好成绩?
也许'predictions.where(“prediction!='NaN'”))''有效。 – IceMimosa