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A Scala script that takes a CSV as input on stdin, produces a pivot table on two columns using a count() function and outputs the pivot table to stdout.
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import collection.mutable | |
import io.Source | |
import java.io.FileInputStream | |
def toIntOption(s: String): Option[Int] = try { Some(s.toInt) } catch { case e: NumberFormatException => None } | |
val intArgs = args.map(toIntOption).flatten | |
if (args.length != 2 && intArgs.length != 2) { | |
System.err.println("usage: <x_column_number> <y_column_number>") | |
sys.exit(1) | |
} | |
// You can change these if you need different behaviour. | |
val containsColumnHeaders = true | |
val containsRowHeaders = false | |
val inputStream = System.in | |
//val inputStream = new FileInputStream("survey.csv") | |
val lines = Source.fromInputStream(inputStream).getLines().toBuffer | |
var cells = lines map { _.split(',').toBuffer } | |
if (containsColumnHeaders) | |
cells = cells.drop(1) | |
if (containsRowHeaders) { | |
cells = cells map { _.drop(1) } | |
} | |
val argToIndex = if (containsRowHeaders) 2 else 1 | |
val (column1Index, column2Index) = (intArgs(0) - argToIndex, intArgs(1) - argToIndex) | |
val map = new mutable.HashMap[(String, String), Int] | |
def pairInRow(row: mutable.Buffer[String]): (String, String) = (row(column1Index), row(column2Index)) | |
// You could change the pivot aggregation fuctnion from count() to soemthing else here | |
// by changing 'rows.size' to some other calculation, e.g. (rows.map{_.toInt}).sum | |
val pairCounts: Map[(String, String), Int] = (for ((pair, rows) <- (cells groupBy pairInRow)) yield (pair, rows.size)).toMap | |
val outputColumns = (pairCounts.keys map {_._1}).toSet.toSeq.sorted | |
val outputRows = (pairCounts.keys map {_._2}).toSet.toSeq.sorted | |
for (column <- outputColumns) { | |
print(',') | |
print(column) | |
} | |
println() | |
for (row <- outputRows) { | |
print(row) | |
for (column <- outputColumns) { | |
print(',') | |
print(pairCounts.getOrElse((column, row), "")) | |
} | |
println() | |
} |
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