I would like to getLine from a Source and convert it to a tuple (Int, Int). I've did it using foreach.
val values = collection.mutable.ListBuffer[(Int, Int)]()
Source.fromFile(invitationFile.ref.file).getLines().filter(line => !line.isEmpty).foreach(line => {
val value = line.split("\\s")
values += ((value(0).toInt, (value(1).toInt)))
})
What's the best way to write the same code without use foreach?
Use map, it builds a new list for you:
Source.fromFile(invitationFile.ref.file)
.getLines()
.filter(line => !line.isEmpty)
.map(line => {
val value = line.split("\\s")
(value(0).toInt, value(1).toInt)
})
.toList()
foreach should be a final operation, not a transformation.
In your case, you want to use the function map
val values = Source.fromFile(invitationFile.ref.file).getLines()
.filter(line => !line.isEmpty)
.map(line => line.split("\\s"))
.map(line => (line(0).toInt, line(1).toInt))
Using a for comprehension:
val values = for(line <- Source.fromFile(invitationFile.ref.file).getLines(); if !line.isEmpty) {
val splits = line.split("\\s")
yield (split(0).toInt, split(1).toInt)
}
for comprehension vs a map ?
fors are syntactic sugar. See stackoverflow.com/questions/1052476/what-is-scalas-yield/…. They'll get compiled into map calls (among other calls). I find fors easier to read then a bunch of chained map calls.