Replace rdd with dataframe functions in Histogram analyzer (awslabs#586)

Co-authored-by: Shriya Vanvari <[email protected]>

src/main/scala/com/amazon/deequ/analyzers/Histogram.scala

@@ -84,11 +84,26 @@ case class Histogram(
       case Some(theState) =>
         val value: Try[Distribution] = Try {
 
-          val topNRows = theState.frequencies.rdd.top(maxDetailBins)(OrderByAbsoluteCount)
+          val countColumnName = theState.frequencies.schema.fields
+            .find(field => field.dataType == LongType && field.name != column)
+            .map(_.name)
+            .getOrElse(throw new IllegalStateException(s"Count column not found in the frequencies DataFrame"))
+
+          val topNRowsDF = theState.frequencies
+            .orderBy(col(countColumnName).desc)
+            .limit(maxDetailBins)
+            .collect()
+
           val binCount = theState.frequencies.count()
 
-          val histogramDetails = topNRows
-            .map { case Row(discreteValue: String, absolute: Long) =>
+          val columnName = theState.frequencies.columns
+            .find(_ == column)
+            .getOrElse(throw new IllegalStateException(s"Column $column not found"))
+
+          val histogramDetails = topNRowsDF
+            .map { row =>
+              val discreteValue = row.getAs[String](columnName)
+              val absolute = row.getAs[Long](countColumnName)
               val ratio = absolute.toDouble / theState.numRows
               discreteValue -> DistributionValue(absolute, ratio)
             }