mean, standard deviation

MobileResponseTimeSpec.scala

import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics
import org.scalatest.{FlatSpec, Matchers}

import scala.io.Source

class MobileResponseTimeSpec extends FlatSpec with Matchers {
  val FILE_NAME = "/Users/msbaek/Downloads/res_time.txt"
  val NINETY = 90.0
  val THREE_SECONDS = 3.0
  val TEN_SECONDS = 10.0
  
  "90 percentile ResponseTime" should "below 3 seconds" in {
    val doubles = Source.fromFile(FILE_NAME).getLines().map(_.toDouble).filter(_ < TEN_SECONDS)
    val descriptiveStatistics = new DescriptiveStatistics()
    doubles.foreach(descriptiveStatistics.addValue(_))
    
    printf("mean   = %.2f\n", descriptiveStatistics.getMean)
    printf("stddev = %.2f\n", descriptiveStatistics.getStandardDeviation)
    printf("90p    = %.2f\n", descriptiveStatistics.getPercentile(NINETY))
    
    assert(descriptiveStatistics.getPercentile(NINETY) < THREE_SECONDS)
  }
}