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如何在spark rdd生成中处理CSV文件列?

  •  0
  • Joseph Hwang  · 技术社区  · 8 年前

    这是我的Java spark代码。这是Spark CSV数据格式。

    "f_name","l_name","job","gender","age","salary"
    "Elsdon","Jaycob","Java programmer","male",43,2000
    "Tamsen","Brittany","Java programmer","female",23,1500
    "Floyd","Donny","Java programmer","male",33,1800
    

    我生成了包含上述数据的Person类

    public class Person implements Serializable {
    
        private String firstName;
        private String lastName;
        private String job;
        private String gender;
        private int salary;
        private int age;
    
        public Person(String firstName, String lastName, String job, String gender, int age, int salary) {
    
            this.firstName = firstName;
            this.lastName = lastName;
            this.job = job;
            this.gender = gender;
            this.age = age;
            this.salary = salary;
            }
    ... getter and setter method.
    

    下面的代码尝试使用spark Java client生成Java RDD。

    SparkConf sc = new SparkConf().setAppName("SparkTest").setMaster("local[*]");
    JavaSparkContext jsc = new JavaSparkContext(sc);
    JavaRDD<String> rdd_text = jsc.textFile("file:///" + srcDir + srcFile);
    
    
    String[] header = rdd_text.map(line -> line.split(",")).first();
    System.out.println(header[4]); // "age" is printed
    JavaRDD<Person> persons = rdd_text.filter(line -> line.split(",")[4] != header[4]).map(
       line -> {
          String[] info = line.split(",");
    
          System.out.println(info[4]); //43,23,33,"age" are printed
    
          Person p = new Person(info[0], info[1], info[2], info[3], 
                                        Integer.parseInt(info[4]), Integer.parseInt(info[5]));
    
         return p;
    });
    
    System.out.println(persons.collect());
    

    系统出来println(信息[4])代码行打印:

    43
    23
    33
    "age"
    

    然后抛出以下异常,

    java.lang.NumberFormatException: For input string: ""age""
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.lang.Integer.parseInt(Integer.java:569)
        at java.lang.Integer.parseInt(Integer.java:615)
        at com.aaa.spark.JavaClient.lambda$2(JavaClient.java:33)
        at org.apache.spark.api.java.JavaPairRDD$$anonfun$toScalaFunction$1.apply(JavaPairRDD.scala:1040)
        at scala.collection.Iterator$$anon$11.next(Iterator.scala:409)
        at scala.collection.Iterator$class.foreach(Iterator.scala:893)
        at scala.collection.AbstractIterator.foreach(Iterator.scala:1336)
        at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:59)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:104)
        at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:48)
        at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:310)
        at scala.collection.AbstractIterator.to(Iterator.scala:1336)
        at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:302)
        at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1336)
        at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:289)
        at scala.collection.AbstractIterator.toArray(Iterator.scala:1336)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:936)
        at org.apache.spark.rdd.RDD$$anonfun$collect$1$$anonfun$13.apply(RDD.scala:936)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2062)
        at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:2062)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:87)
        at org.apache.spark.scheduler.Task.run(Task.scala:108)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:335)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:748)
    

    我不知道哪一行有错误代码以及原因。 System.out.println(info[4]) 打印“age”字符串值。

    1 回复  |  直到 8 年前
        1
  •  1
  •   pasha701    8 年前

    您可以像平常一样读取文本文件,而不是CSV:

     jsc.textFile("file:///" + srcDir + srcFile);
    

    文件第一行的标题(带有“age”值)也由Integer处理。parseInt(信息[4]),这是错误的原因。

    Spark有解析CSV的特定方法,您可以使用它们:

    https://github.com/databricks/spark-csv

    最新的Spark版本中有CSV解析,请查看文档。

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