CODEWITHSUNDEEP
stringscala
blue-sky
blue-sky

Reputation: 53786

Removing characters from List of Strings

To remove characters from a List of Strings I use : 

val validLines : List[String] = List("test[" , "test]")

    val charsToClean: List[String] = List("\"", "[", "]", "'")

    val filtered = validLines.map(line => line.replace(charsToClean(0), "")
      .replace(charsToClean(1), "")
      .replace(charsToClean(2), "")
      .replace(charsToClean(3), ""))

I'm attempting use a inner map function instead of hard coding the positions of the chars to replace : 

val filtered1 : List[String] = validLines.map(line => charsToClean.map {c => line.replace(c , "")  })

But receive compiler error : 

mismatch; found : List[List[String]] required: List[String]

Should result of line.replace(c , "") not be returned ?

Upvotes: 4

Views: 3393

Answers (4)

om-nom-nom
om-nom-nom

Reputation: 62835

No, because your code is more like: for every string and for every unwanted char, return replacement for this very symbol (n^2 strings).

What you probably wanted to do can be achieved using the following snippet: 

val rawLines : List[String] = List("test[" , "test]")
val blacklist: Set[Char] = Set('\"', '[', ']' ,''')
rawLines.map(line => line.filterNot(c => blacklist.contains(c)))
// res2: List[String] = List(test, test)

Or alternatively, using regexp, as @ka4eli has shown in his answer.

Upvotes: 8

elm
elm

Reputation: 20405

Equivalent to @om-nom-nom though using a for comprehension syntax; given a set of characters to erase,

val charsToClean = """"[]'""".toSet

then 

for (l <- validLines) yield l.filterNot(charsToClean)

where implicit set inclusion Char => Boolean function is applied in filterNot.

Upvotes: 1

Helder Pereira
Helder Pereira

Reputation: 5756

You need to use foldLeft instead of map.

val validLines : List[String] = List("test[" , "test]")

val charsToClean: List[String] = List("\"", "[", "]", "'")

val filtered : List[String] = validLines.map(line => charsToClean.foldLeft(line)(_.replace(_, "")))

Upvotes: 3

ka4eli
ka4eli

Reputation: 5424

replaceAll can contain more complex regex constructed with | (or) operator:

validLines.map(_.replaceAll("\\[|\\]|'|\"", ""))

Upvotes: 4

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