how to replace null with 0 in scala array

Question

I am a scala beginner and I face a problem when I am doing my homework because there is null in the text file for example (AFG,Asia,Afghanistan,2020-02-24,1.0,1.0,,,,,0.026,0.026). So, I need to replace the null in array with zero. I read the scala array members and try the update and filter method but I cannot solve it. Can someone help me?

    val filename = "relevant.txt" //Access File
val rf = Source.fromFile(filename).getLines.toArray //Read File as Array


for(line <- rf){ //for loop
  line.(**How to replace the null with 0?**)

  //println(line.split(",")(0))
  if (line.split(",")(0).trim().equalsIgnoreCase(iso_code)){ //check for correct ISO CODE , ignores the casing of the input
    
  total_deaths += line.split(",")(4).trim().toDouble //increases based on the respective array position
 
  sum_of_new_deaths += line.split(",")(5).trim().toDouble
 
  record_count += 1 //increment for each entry

  }
}

Do you mean you want AFG,Asia,Afghanistan,2020-02-24,1.0,1.0,,,,,0.026,0.026 become AFG,Asia,Afghanistan,2020-02-24,1.0,1.0,0,0,0,0,0.026,0.026 ? — yyyy
– yyyy, Commented Nov 12, 2021 at 14:15

yyyy · Accepted Answer · 2021-11-13 05:17:46Z

1

val cells = line.split(",")
                .map(_.trim)
                .map(it => if (it.isEmpty) "0" else it)

Then you can use it like total_deaths += cells(4).toDouble

BTW, null usually refers to "null pointer" in scala.

In your case, you don't have any "null pointer", you just have "empty string"

answered Nov 13, 2021 at 5:17

yyyy

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Comments

Luis Miguel Mejía Suárez · Accepted Answer · 2021-11-12 13:54:42Z

0

What you may do is something like this:

for (line <- rf) {
  val data = line.split(',').toList.map(str => Option(str).filter(_.nonEmpty))
}

That way data would be a List[Option[String]] where empty values will be None, then you may use pattern matching to extra the data you want.

edited Nov 12, 2021 at 13:54

answered Nov 12, 2021 at 13:40

Luis Miguel Mejía Suárez

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Philluminati · Accepted Answer · 2021-11-12 14:07:07Z

0

if you had to apply the change where you want:

//line.(**How to replace the null with 0?**)

you could do:

val line2 = if (line.trim().isEmpty) "," else line

then use line2 everywhere else.

As a side thing, if you want to do something more scala, replace .toArray with .toList and have a look at how map, filter, sum etc work.

answered Nov 12, 2021 at 14:07

Philluminati

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