4.01 Examples

Examples

Read Stock prices and calculate moving average

An example REPL session. Let's read some stock prices and calculate the 5 period moving average:

scala> import java.util.Date
import java.util.Date

scala> implicit val dmy = new DateConverter("dd-MMM-yy")  // tell the parser how to read your dates
dmy: com.github.marklister.collections.io.DateConverter = com.github.marklister.collections.io.DateConverter@26d606

scala> val p=CsvParser[Date,Int,Int,Int,Int]  //Date, close, High, Low, Volume
p: com.github.marklister.collections.io.CsvParser5[java.util.Date,Int,Int,Int,Int] = com.github.marklister.collections.io.CsvParser5@1584d9

scala> val prices=p.parseFile("abil.csv", hasHeader=true, delimiter="\t")
prices: com.github.marklister.collections.immutable.CollSeq5[java.util.Date,Int,Int,Int,Int] = 
(Mon Apr 30 00:00:00 AST 2012,3885,3922,3859,4296459)
(Wed May 02 00:00:00 AST 2012,3880,3915,3857,3127464)
(Thu May 03 00:00:00 AST 2012,3920,3948,3874,3080823)
(Fri May 04 00:00:00 AST 2012,3909,3952,3885,2313354)
(Mon ....

scala> val ma= prices._2.sliding(5).toList.map(_.mean)
ma: List[Double] = List(3889.4, 3866.4, 3830.4, 3792.8, 3763.0, 3724.4, 3700.4, 3692.6, 3670.2, 3627.2, 3615.6, 3615.6, 3596.6, 3599.0, 3612.0, 3609.8, 3605.6, 3611.0, 3611.0, 3606.0, 3614.2, 3612.4, 3629.0, 3634.6, 3659.4, 3661.0, 3657.2, 3645.2, 3628.4, 3616.4, 3632.8, 3668.8, 3702.6, 3745.4, 3781.0, 3779.6, 3755.4, 3727.4, 3689.4, 3650.2, 3638.8, 3641.8, 3648.2, 3663.2, 3671.0, 3649.4, 3624.4, 3595.0, 3559.0, 3518.0, 3505.8, 3495.8, 3505.8, 3531.2, 3570.8, 3589.0, 3613.0, 3620.8, 3624.4, 3635.4, 3661.0, 3667.0, 3686.6, 3703.6, 3720.0, 3722.4, 3692.4, 3619.0, 3553.4, 3473.4, 3413.2, 3400.0, 3422.8, 3427.4, 3433.6, 3434.0, 3425.6, 3403.8, 3396.6, 3388.6, 3376.0, 3353.6, 3318.6, 3291.8, 3260.6, 3240.0, 3225.0, 3226.0, 3218.2, 3232.2, 3219.6, 3226.0, 3234.0, 3251.0, 3271.0, 3312.4, 3341....

scala> prices._1.drop(5).zip(ma) //moving average zipped with date
res0: Seq[(java.util.Date, Double)] = List((Tue May 08 00:00:00 AST 2012,3889.4), (Wed May 09 00:00:00 AST 2012,3866.4), (Thu May 10 00:00:00 AST 2012,3830.4), (Fri May 11 00:00:00 AST 2012,3792.8), (Mon May 14 00:00:00 AST 2012,3763.0), (Tue May 15 00:00:00 AST 2012,3724.4), (Wed May 16 00:00:00 AST 2012,3700.4), (Thu May 17 00:00:00 AST 2012,3692.6), (Fri May 18 00:00:00 AST 2012,3670.2), (Mon May 21 00:00:00 AST 2012,3627.2), (Tue May 22 00:00:00 AST 2012,3615.6), (Wed May 23 00:00:00 AST 2012,3615.6), (Thu May 24 00:00:00 AST 2012,3596.6), (Fri May 25 00:00:00 AST 2012,3599.0), (Mon May 28 00:00:00 AST 2012,3612.0), (Tue May 29 00:00:00 AST 2012,3609.8), (Wed May 30 00:00:00 AST 2012,3605.6), (Thu May 31 00:00:00 AST 2012,3611.0), (Fri Jun 01 00:00:00 AST 2012,3611.0), (Mon Jun 04 0...
scala> 

Read csv that has field parse errors

Note: this converter is now provided as standard in the distribution.

scala> import scala.util.Try
import scala.util.Try

scala> implicit object optionIntConverter extends GeneralConverter[Option[Int]]{
 | def convert(x:String)=Try(x.trim.toInt).toOption
 | }

defined module optionIntConverter

scala> CsvParser[String,Option[Int]].parseFile("badly-formed.csv")
res3: com.github.marklister.collections.immutable.CollSeq2[String,Option[Int]] = 
CollSeq((Jan,Some(10)),
        (Feb,None),
        (Mar,Some(25)))

Calculate an aircraft's moment in in-lb

scala> val aircraftLoading=CollSeq(("Row1",86,214),("Row4",168,314),("FwdCargo",204,378)) //Flight Station, Mass kg, Arm in
aircraftLoading: com.github.marklister.collections.immutable.CollSeq3[java.lang.String,Int,Int] = 
(Row1,86,214)
(Row4,168,314)
(FwdCargo,204,378)

scala> val pounds = aircraftLoading._2.map(_ * 2.2)  //convert kg -> lb
pounds: Seq[Double] = List(189.20000000000002, 369.6, 448.8)

scala> val moment = pounds.zip(aircraftLoading._3).map(x=>x._1*x._2)
moment: Seq[Double] = List(40488.8, 116054.40000000001, 169646.4)

scala> moment.sum
res1: Double = 326189.6