How do I get the first letter in each word in scala?

Question

If I have the phrase "New York City" how do I get the first letter of each word? My googling has only shown me how to capitalize the first letter in each word, which is seemingly different from what I'm trying to do.

Given my limited knowledge of Scala, I could probably do this procedurally but I was hoping someone could shed some Scala knowledge on me and show me an example that depicts a functional approach to this problem.

Answer 1

All other versions work fine but in order to avoid failure with badly formatted strings (two blanks in a row, empty string), use

"New York City".split(" ").flatMap(_.headOption).mkString

which also works for

"New  York  City".split(" ").flatMap(_.headOption).mkString

or even

"".split(" ").flatMap(_.headOption).mkString

As suggested by dhg, one may want to use a more appropriate regex such as "\\s+" as well. But then one might just as well use something even more appropriate:

"""\w+""".r.findAllIn("New  York  City").map(_.head).mkString

(In here the /\w+/ should hopefully spare us from pathological cases so we can go with the .head version.)

Answer 2

scala> "New York City".split(" ").map(_.head).mkString
res5: String = NYC

This splits by " " into an Array of words. Then we map over that array and call String.head which gets the first character.

Answer 3

"New York City".split(" ").toList.map(_(0))

gives the characters:

List[Char] = List(N, Y, C)

If you want a string use mkString on the List[Char]:

"New York City".split(" ").toList.map(_(0)) mkString

to get:

String = NYC

Answer 4

"New York City".split(" ").map(_.charAt(0))

Will give you a char array

Answer 5

Here's an alternative to using split (Regex).

The trick here is to use zip to allow testing of the current and previous character in the same iteration as you traverse the String, word boundaries consist of any letter preceded by a non-letter.

The two special cases, first and last letter, are handled by 1) prepending a space to a copy of the String which also sets up the 1 character skew required for the zip and 2) zip truncates partial pairs.

val s = "\n1New\n\t \t \tYork --City\n\t"


def firstLetters(s: String) = {
  " "+s zip s collect {case (w, c) if ! w.isLetter && c.isLetter => c}
}

firstLetters(s)

returns

Vector(N, Y, C)