spark how to remove last line in a csv file

问题

I am new to spark I want to remove header and last line from a csv file

      Notes  xyz
     "id","member_id"
     "60045257","63989975",
     "60981766","65023535",

     Total amount:4444228900
     Total amount: 133826689

I want to remove line Notes xyz ,Total amount:4444228900 and Total amount: 133826689 from the file .I have removed the first line from the file

val dfRetail = sc.textFile("file:////home/cloudera/Projects/Project3/test/test_3.csv");
var header=dfRetail.first();
var final_data=dfRetail.filter(row => row!=header);

How to remove the last lines ?

回答1:

Use zipWithIndex and then filter by index:

val total = dfRetail.count();
val withoutFooter = dfRetail.zipWithIndex()
                            .filter(x => x._2 < total - 3)
                            .map (x => x._1)

It will map each line to pair (line, index). Then you filter this RDD, selecting only those with index lower than total number of objects - 3 - so without footer. When you map it to only first element of tuple, so for line of document

You can also use mapPartitionsWithIndex:

val withoutFooter = dfRetail.mapPartitionsWithIndex { (idx, iter) => 
     val size = iter.size();
     if (idx == noOfTotalPartitions) {
         iter.take(size - 3)
     }
     else iter 
});

It's working in the same way, but may be faster

来源：https://stackoverflow.com/questions/42763806/spark-how-to-remove-last-line-in-a-csv-file