我正在尝试将预测映射到 LinearRegression 模型,以便将它们传递到 BinaryClassificationMetrics 对象:
// Make predictions on test documents. cvModel uses the best model found (lrModel).
DataFrame predictions = cvModel.transform(testingFrame);
JavaRDD<Tuple2<Object, Object>> scoreAndLabels = predictions.map(
new Function<Row, Tuple2<Object, Object>>() {
@Override
public Tuple2<Object, Object> call(Row r) {
Double score = r.getDouble(1);
return new Tuple2<Object, Object>(score, r.getDouble(0));
}
}
);
BinaryClassificationMetrics metrics
= new BinaryClassificationMetrics(JavaRDD.toRDD(scoreAndLabels));
但是,当我调用 时predictions.map(...)
,出现以下编译错误:
method map in class DataFrame cannot be applied to given types;
required: Function1<Row,R>,ClassTag<R>
found: <anonymous Function<Row,Tuple2<Object,Object>>>
reason: cannot infer type-variable(s) R
(actual and formal argument lists differ in length)
where R is a type-variable:
R extends Object declared in method <R>map(Function1<Row,R>,ClassTag<R>)
关于如何映射预测 DataFrame 的数据的任何建议?