3

JavaでRDD.flatMap関数を使用しました。今、DataFrames を試しています。

彼らが言うには：

public <R> RDD<R> flatMap(scala.Function1<org.apache.spark.sql.Row,
    scala.collection.TraversableOnce<R>> f, scala.reflect.ClassTag<R> evidence$4)

最初にこの DataFrame のすべての行に関数を適用し、次に結果を平坦化することにより、新しい RDD を返します。

定義: インターフェース RDDApi 内の flatMap

しかし、これを試してみるとFunction1、実装されていない多くのメソッドをオーバーライドする必要がありました。これは私が得るものです：

    RDD<Row> res = df.flatMap(new Function1<Row, TraversableOnce<Row>>() {

        @Override
        public <A> Function1<Row, A> andThen(
                Function1<TraversableOnce<Row>, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcDD$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcDF$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcDI$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcDJ$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcFD$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcFF$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcFI$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcFJ$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcID$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcIF$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcII$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcIJ$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcJD$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcJF$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcJI$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcJJ$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcVD$sp(
                Function1<BoxedUnit, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcVF$sp(
                Function1<BoxedUnit, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcVI$sp(
                Function1<BoxedUnit, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcVJ$sp(
                Function1<BoxedUnit, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcZD$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcZF$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcZI$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<Object, A> andThen$mcZJ$sp(
                Function1<Object, A> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public TraversableOnce<Row> apply(Row arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public double apply$mcDD$sp(double arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public double apply$mcDF$sp(float arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public double apply$mcDI$sp(int arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public double apply$mcDJ$sp(long arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public float apply$mcFD$sp(double arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public float apply$mcFF$sp(float arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public float apply$mcFI$sp(int arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public float apply$mcFJ$sp(long arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public int apply$mcID$sp(double arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public int apply$mcIF$sp(float arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public int apply$mcII$sp(int arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public int apply$mcIJ$sp(long arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public long apply$mcJD$sp(double arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public long apply$mcJF$sp(float arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public long apply$mcJI$sp(int arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public long apply$mcJJ$sp(long arg0) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public void apply$mcVD$sp(double arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void apply$mcVF$sp(float arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void apply$mcVI$sp(int arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public void apply$mcVJ$sp(long arg0) {
            // TODO Auto-generated method stub

        }

        @Override
        public boolean apply$mcZD$sp(double arg0) {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public boolean apply$mcZF$sp(float arg0) {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public boolean apply$mcZI$sp(int arg0) {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public boolean apply$mcZJ$sp(long arg0) {
            // TODO Auto-generated method stub
            return false;
        }

        @Override
        public <A> Function1<A, TraversableOnce<Row>> compose(
                Function1<A, Row> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcDD$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcDF$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcDI$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcDJ$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcFD$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcFF$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcFI$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcFJ$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcID$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcIF$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcII$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcIJ$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcJD$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcJF$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcJI$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcJJ$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, BoxedUnit> compose$mcVD$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, BoxedUnit> compose$mcVF$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, BoxedUnit> compose$mcVI$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, BoxedUnit> compose$mcVJ$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcZD$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcZF$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcZI$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }

        @Override
        public <A> Function1<A, Object> compose$mcZJ$sp(
                Function1<A, Object> arg0) {
            // TODO Auto-generated method stub
            return null;
        }
    }, evidence$4);

これは奇妙に見えますが、次のように作成evidence$4しました。

ClassTag<Row> evidence$4 = scala.reflect.ClassTag$.MODULE$.apply(Row.class);

私の意図は、flatMap（もちろんRDDではなくDataFrameで）いじることです。だから私は変更する必要はありませんRow。入力を変更せずにそのまま返すことができます。

applyしたがって、メソッドのみを変更する必要があると思います。

    @Override
    public TraversableOnce<Row> apply(Row arg0) {
        // TODO Auto-generated method stub
        return null;
    }

しかし、繰り返しますが、どうやってTraversableOnce<Row>から取得する必要がありRowますか?

また、私が試している方法は正しいですか？または、何か不足していますか？

Apache Spark 1.3.1 を使用しています

4

1 に答える 1

1

次のようなことを行う必要があります。

RDD<Row> res = df.flatMap(new AbstractFunction1<Row, TraversableOnce<Row>>() {
  public TraversableOnce<Row> apply(Row row) {
    return new ListSet<Row>().$plus(row); //Note the updated list is returned from $plus()
  }
}, evidence$4);

これは と同様に機能しmapますが、より自由に変更できます。たとえば、物事を除外するためnew ListSet<Row>()に、返したいときに空を返すか、現在の動作を維持できます。flatMap非常に柔軟です。

(Java コレクションから Scala コレクションへの変換は簡単ではないようです。)

于 2015-05-25T15:48:07.170 に答える