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I want instance's array just like as follow;
var ExampleObj = List(10)(new Obj)
Then I want to use this as;
var (hoge0, hoge1) = ExampleObj(2)(foo0, foo1, foo2)
The (new Obj) makes type mismatch.
[error] found : unittest.Obj
[error] required: Int
I do package unittest for Obj class.
What I make misunderstand ?
Could you please point out that point and how to solve it ?
If I understood your question correctly, you're trying to create a List with 10 instances of Obj class?
It can be done using fill method, like that:
List.fill(10)(new Obj)
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Consider the following list(1,1,2,2,3,4,4,5,5) I want to print only 3. Since it is the unique one. Can someone help me with the Scala code.
It's not a Spark question, but this function would do it for Scala
def uniqueElems[T](lst: Seq[T]) = {
lst.groupBy(identity).collect { case v if v._2.length == 1 => v._2.head }
}
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im trying to convert a scala list of eithers, as such:
List(Left(3),Left(4),Left(1),Left(5))
Into a either of a list Either[List[Int],Int] like this?
Left(3,4,1,5)
Only using flatmap, map or fold?
ive been hammering at it for a while now and can simply not make it work
Assumed:
val a = List(Left(1), Left(2), Left(3)) // for example
Then following will return a Left[List[Int]]:
Left(a.map(_.value))
// Left(List(1, 2, 3))
Then you can extract the values out of the list, which I don't thin is generally a good idea.
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I have a trait like this:
trait MyBag[A]{
def add(elem: A): This
}
What is the :This return type? Does this mean the add function returns an instance of MyBag?
This is just the name of a type that is defined somewhere else that you are not showing us. The compiler doesn't speak English, it doesn't care whether a type is named This or Foo or Fgjbgjzdz55437365643w.
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typealias Names = String
typealias Works = String
let a: Names = Names()
let b: Works = Works()
if a is Names {// a is not Works
}
How do I know if "a" belongs to "Names" instead of "Works"?
Thanks!
How do I know if "a" belongs to "Names" instead of "Works"?
You don’t, because it doesn’t. They are all names for the same thing. They are completely interchangeable. There is no sense in which something is a Names but not a Works.
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I'm putting some test cases and having lots of parameters yet it is cumbersome and not so easy to understand putting them into a liner in scala. I rather specify in a visually acceptable manner but correctly parse them in scala...
I would use String Interpolation to define the arguments such as below
val kafkaServers = "server1:9092,server2:9092"
val pleasentArgs = s"""
--master='spark://someserver'
--metricWindowSize=50
--outputDirectory='/tmp/someGoodDirectory'
--zkQuorum=$zkQuorum
--saveToHDF=false
--userName='jack#somewhereElse.com'
--kafkaServers=$kafkaServers
"""
And have a method to clean up all the newline, tab etc characters and then generate the args as shown below:
def cleanUp(str:String) = str.split('\n').map(_.trim.filter(_ >= ' ')).mkString(" ")
def genArgs(args:String): Array[String] =cleanUp(args).split(" ").filter(!_.trim.isEmpty)
So eventually we can just call genArgs method
val args = genArgs(pleasentArgs)