How to create a DataFrame from a text file in Spark

Question

I have a text file on HDFS and I want to convert it to a Data Frame in Spark   I am using the Spark Context to load the file and then try to generate individual columns from that file    val myFile   sc textFile  file txt   val myFile1   myFile map x  gt x split         After doing this  I am trying the following operation   myFile1 toDF     I am getting an issues since the elements in myFile1 RDD are now array type   How can I solve this issue

User · Answer

val df   spark read textFile  abc txt    case class Abc  amount Int  types  String  id Int     columns and data types  val df2   df map rec  gt Amount rec 0  toInt  rec 1   rec 2  toInt   rdd2 printSchema     root   -- amount  integer  nullable   true    -- types  string  nullable   true    -- id  integer  nullable   true

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A txt File with PIPE     delimited file can be read as    df   spark read option  quot sep quot    quot   quot   option  quot header quot    quot true quot   csv  quot s3   bucket name folder path file name txt quot

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You will not able to convert it into data frame until you use implicit conversion   val sqlContext   new SqlContext new SparkContext     import sqlContext implicits     After this only you can convert this to data frame  case class Test id String filed2 String   val myFile   sc textFile  file txt    val df  myFile map  x   gt  x split        map  x  gt  Test x 0  x 1     toDF

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If you want to use the toDF method  you have to convert your RDD of Array String  into a RDD of a case class  For example  you have to do   case class Test id String filed2 String  val myFile   sc textFile  file txt   val df  myFile map  x   gt  x split        map  x  gt  Test x 0  x 1     toDF

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You can read a file to have an RDD and then assign schema to it  Two common ways to creating schema are either using a case class or a Schema object  my preferred one   Follows the quick snippets of code that you may use   Case Class approach  case class Test id String name String  val myFile   sc textFile  file txt   val df  myFile map  x   gt  x split        map  x  gt  Test x 0  x 1     toDF     Schema Approach  import org apache spark sql types   val schemaString    id name  val fields   schemaString split      map fieldName   gt  StructField fieldName  StringType  nullable true   val schema   StructType fields   val dfWithSchema   sparkSess read option  header   false   schema schema  csv  file txt   dfWithSchema show     The second one is my preferred approach since case class has a limitation of max 22 fields and this will be a problem if your file has more than 22 fields

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Update - as of Spark 1 6  you can simply use the built-in csv data source   spark  SparkSession      create the Spark Session val df   spark read csv  file txt     You can also use various options to control the CSV parsing  e g    val df   spark read option  header    false   csv  file txt     For Spark version  lt  1 6  The easiest way is to use spark-csv - include it in your dependencies and follow the README  it allows setting a custom delimiter      can read CSV headers  if you have them   and it can infer the schema types  with the cost of an extra scan of the data     Alternatively  if you know the schema you can create a case-class that represents it and map your RDD elements into instances of this class before transforming into a DataFrame  e g    case class Record id  Int  name  String   val myFile1   myFile map x  gt x split       map     case Array id  name    gt  Record id toInt  name      myFile1 toDF      DataFrame will have columns  id  and  name

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I know I am quite late to answer this but I have come up with a different answer   val rdd   sc textFile   home training mydata file txt    val text   rdd map lines lines split       map arrays  gt  ararys 0  arrays 1    toDF  id   name   show

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I have given different ways to create DataFrame from text file  val conf   new SparkConf   setAppName appName  setMaster  local   val sc   SparkContext conf    raw text file  val file   sc textFile  C   vikas  spark  Interview  text txt   val fileToDf   file map   split       map case Array a b c    gt    a b toInt c   toDF  name   age   city   fileToDf foreach println       spark session without schema  import org apache spark sql SparkSession val sparkSess    SparkSession builder   appName  SparkSessionZipsExample    config conf  getOrCreate    val df   sparkSess read option  header     false   csv  C   vikas  spark  Interview  text txt   df show     spark session with schema  import org apache spark sql types   val schemaString    name age city  val fields   schemaString split      map fieldName   gt  StructField fieldName   StringType  nullable true   val schema   StructType fields   val dfWithSchema   sparkSess read option  header     false   schema schema  csv  C   vikas  spark  Interview  text txt   dfWithSchema show     using sql context  import org apache spark sql SQLContext  val fileRdd    sc textFile  C   vikas  spark  Interview  text txt   map   split       map x    gt  org apache spark sql Row x      val sqlDf   sqlCtx createDataFrame fileRdd schema  sqlDf show

[scala] How to create a DataFrame from a text file in Spark

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