scala - 为什么我无法在读取 xml 和过滤器时根据此条件进行过滤

Question

我有一个示例代码

import org.apache.spark.sql.Row
import scala.xml._

object reading_xml {
  def main(args: Array[String]): Unit = {
    //I have 42 Millions of records
    val records = List(
      "<root><c1>v1</c1><c2>v2</c2><c3>v3</c3><c4>v4</c4><c5>20181104</c5></root>",
      "<root><c1>v1</c1><c2>v2</c2><c3>v3</c3><c4>v4</c4><c5>20181102</c5></root>",
      "<root><c1>v1</c1><c2>v2</c2><c3>v3</c3><c4>v4</c4><c5>20181102</c5></root>",
      "<root><c1>v1</c1><c2>v2</c2><c3>v3</c3><c4>v4</c4><c5>20181106</c5><c6>v6</c6></root>"
    )
    import org.apache.spark.sql.SparkSession
    val spark = SparkSession.builder().master("local").getOrCreate()
    import spark.implicits._
    val df = records.toDF()
    df.show()
    val rdd = df.rdd.map(line => Row.fromSeq(
      "BNK"
    :: scala.xml.XML.loadString("<?xml version='1.0' encoding='utf-8'?>" + line(0)).child
      .filter(elem =>
        elem.label == "c1" 
        || elem.label == "c2" 
        || elem.label == "c3" 
        || (elem.label == "c5" && elem.text =="20181106")
      ).map(elem =>  elem.label+"@"+elem.text).toList)
    )
    rdd.take(100).foreach(println)

实际输出:

[BNK,c1@v1,c2@v2,c3@v3]
[BNK,c1@v1,c2@v2,c3@v3]
[BNK,c1@v1,c2@v2,c3@v3]
[BNK,c1@v1,c2@v2,c3@v3,c5@20181106]

我期望的结果是只得到一行。

[BNK,c1@v1,c2@v2,c3@v3,c5@20181106]

我的情况有什么问题或我错过了对 scala_xml 的理解，以及如何获得预期结果？

Answer 1

取决于你想做什么。如果您要查找标签 c1、c2、c3、c5 中的任何一个是否具有 20181106 的值，那么您可能想要这样做。

    (elem.label == "c1" || elem.label == "c2" || elem.label == "c3" || elem.label == "c5")
    && elem.text =="20181106"