Read CSV File to OrderedMap - scala

Question

I'm reading the CSV File and adding data to Map in Scala.
val br = new BufferedReader(new InputStreamReader(new FileInputStream(new File(fileName)), "UTF-8"))
val inputFormat = CSVFormat.newFormat(delimiter.charAt(0)).withHeader().withQuote('"')
import scala.collection.JavaConverters._
import org.apache.commons.csv.{CSVFormat, CSVParser}
val csvRecords = new CSVParser(br, inputFormat).getRecords.asScala
val buffer = for (csvRecord <- csvRecords; if csvRecords != null && csvRecords.nonEmpty)
yield csvRecord.toMap.asScala
buffer.toList
But as the Map is not ordered I'm not able to read the columns in order. Is there any way to read the csvRecords in order?
The CSV file contains comma separated values along with the header. It should generate the output in List[mutable.LinkedHashMap[String, String]] format something like [["fname", "A", "lname", "B"], ["fname", "C", "lname", "D"]].
The above code is working but it is not preserving the order. For Ex: if CSV file contains columns in order fname, lname, the output map is having lname first and fname last.

Answer 1

If I understand you question correctly, here's one way to create a list of LinkedHashMaps with elements in order:
// Assuming your CSV File has the following content:
fname,lname,grade
John,Doe,A
Ann,Cole,B
David,Jones,C
Mike,Duke,D
Jenn,Rivers,E
import collection.mutable.LinkedHashMap
// Get indexed header from CSV
val indexedHeader = io.Source.fromFile("/path/to/csvfile").
getLines.take(1).next.
split(",").
zipWithIndex
indexedHeader: Array[(String, Int)] = Array((fname,0), (lname,1), (grade,2))
// Aggregate LinkedHashMap using foldLeft
val ListOfLHM = for ( csvRecord <- csvRecords ) yield
indexedHeader.foldLeft(LinkedHashMap[String, String]())(
(acc, x) => acc += (x._1 -> csvRecord.get(x._2))
)
ListOfLHM: scala.collection.mutable.Buffer[scala.collection.mutable.LinkedHashMap[String,String]] = ArrayBuffer(
Map(fname -> John, lname -> Doe, grade -> A),
Map(fname -> Ann, lname -> Cole, grade -> B),
Map(fname -> David, lname -> Jones, grade -> C),
Map(fname -> Mike, lname -> Duke, grade -> D),
Map(fname -> Jenn, lname -> Rivers, grade -> E)
)