Add a header before text file on save in Spark

Question

I have some spark code to process a csv file. It does some transformation on it. I now want to save this RDD as a csv file and add a header. Each line of this RDD is already

Answer 1

Slightly diff approach with Spark SQL

From Question: I now want to save this RDD as a CSV file and add a header. Each line of this RDD is already formatted correctly.

With Spark 2.x you have several options to convert RDD to DataFrame

val rdd = .... //Assume rdd properly formatted with case class or tuple
val df = spark.createDataFrame(rdd).toDF("col1", "col2", ... "coln")

df.write
  .format("csv")
  .option("header", "true")  //adds header to file
  .save("hdfs://location/to/save/csv")

Now we can even use Spark SQL DataFrame to load, transform and save CSV file