Removing multiple character types from a string

Question

Is this an acceptable approach for removing multiple character types from a string or is there a better (more efficient way)? The "ilr".contains(_) bit feels a little like cheating considering it will be done for each and every character, but then again, maybe this is the right way. Is there a faster or more efficient way to do this?

val sentence = "Twinkle twinkle little star, oh I wander what you are"

val words = sentence.filter(!"ilr".contains(_))   

// Result: "Twnke twnke tte sta, oh I wande what you ae"

score 34 · Answer 1 · 2013-01-24T09:57:00.527

34

I'd just use Java's good old replaceAll (it takes a regexp):

"Twinkle twinkle little star, oh I wander what you are" replaceAll ("[ilr]", "")
// res0: String = Twnke twnke tte sta, oh I wande what you ae

In contrast to working with chars (as in filtering a Seq[Char]), using regular expressions should be Unicode-safe even if you're working with code points outside the basic multilingual plane. "There Ain't No Such Thing As Plain Text."

edited Jan 24 '13 at 09:57

answered Jan 24 '13 at 07:50

You might have a point there on "outside the BMP". But if you care, you better get busy testing — there's *almost* no such thing as BMP-safe Java software (http://stackoverflow.com/a/2533118/53974). Luckily, the SDK is apparently an exception, if you use the right APIs - and regexps are among the blessed ones. http://www.oracle.com/us/technologies/java/supplementary-142654.html – Blaisorblade Mar 09 '14 at 11:50

score 32 · Accepted Answer · answered Jan 24 '13 at 07:02

32

There would be no significant difference, since there is only 3 characters to remove and no so big string to filter, but you may consider to use Set for this purpose. E.g.

val toRemove = "ilr".toSet
val words = sentence.filterNot(toRemove)

answered Jan 24 '13 at 07:02

om-nom-nom

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Thanks, this version is faster though: val toRemove = List( 'i', 'l', 'r'); val words = sentence.filterNot(toRemove.contains(_)) – alex May 25 '20 at 22:29

Removing multiple character types from a string

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