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=>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?

Answer 1

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 < 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=>x.split(";")).map {
  case Array(id, name) => Record(id.toInt, name)
} 

myFile1.toDF() // DataFrame will have columns "id" and "name"