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

def addHeaderToRdd(sparkCtx: SparkContext, lines: RDD[String], header: String): RDD[String] = {

    val headerRDD = sparkCtx.parallelize(List((-1L, header)))     // We index the header with -1, so that the sort will put it on top.

    val pairRDD = lines.zipWithIndex()

    val pairRDD2 = pairRDD.map(t => (t._2, t._1))

    val allRDD = pairRDD2.union(headerRDD)

    val allSortedRDD = allRDD.sortByKey()

    return allSortedRDD.values
}