scala/scala

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RoelofWobben

@RoelofWobben

so it solved it this way : def earliestFilm = mcTiernan.films.foldLeft(Int.MaxValue) { (current, film) => math.min(current, film.yearOfRelease)

with a hint of the book

but I have another problem that I cannot solve

I have to find the average score of the idbm Rating

so I did this :

val films = directors.flatMap(director => director.films)

    def averageScore:Int = films.foldLeft(0)((a, b) => a.imdbRating + b.imdbRating) / films.length

but now I see this type error :

Error:(60, 58) value imdbRating is not a member of Int
    def averageScore:Int = films.foldLeft(0)((a, b) => a.imdbRating + b.imdbRating) / films.length

Sorixelle

@Sorixelle

What type is films?

RoelofWobben

@RoelofWobben

so a is the acc that holds the answer ?

Sorixelle

@Sorixelle

Oh wait, hang on

Martijn Hoekstra

@martijnhoekstra

try to annotate a and b with the types that you think they have

Sorixelle

@Sorixelle

a isn't the type you think it is

RoelofWobben

@RoelofWobben

Films is a list

Sorixelle

@Sorixelle

Remember, a is your accumulator, and b is the current object

RoelofWobben

@RoelofWobben

aha, that was I already suspected

vijendra singh

@viju0731_twitter

@viju0731_twitter
Batch entry was aborted. Call getNextException to see the cause
how do i call this in scala
any help

getting ths error

how to call getNextException here

Batch Entry 0 insert into PGSQL-Call getNextException to see the cause

this is exact error I am getting

i want to see the real cause why it is failing to update the batch using scala

Sorixelle

@Sorixelle

Hard to help without any context - where are you seeing this error? What are you doing to cause it?

vijendra singh

@viju0731_twitter

i am trying to make call to postgres from scala file

when i am trying to write the data in postgres getting this error

RoelofWobben

@RoelofWobben

Thanks, I think it's time to find out how I can see the type of something in intelij

vijendra singh

@viju0731_twitter

java.sql.BatchUpdateException: Batch entry 0 INSERT INTO

Dominic Egger

@GrafBlutwurst

@RoelofWobben scala is so nice as to put some convinience methods on specific lists. List[Int] has a sum method e.g. List(1,2,3).sum. Though technically I think a foldLeft where you sum and count at the same time is more efficient

Sorixelle

@Sorixelle

@RoelofWobben If you hover over something with Ctrl (or Cmd on macOS), it shows you the type signature

Dominic Egger

@GrafBlutwurst

i think the keyboard shortcut is ctrl+p for showing the signature of a parameter list under the cursor. I'd also recommend rebinding "type info" action in intellij to something better reachable

RoelofWobben

@RoelofWobben

@GrafBlutwurst so I can do something like (films.map(_.idbmRating).sum ?

to count all ratings

Sorixelle

@Sorixelle

That would give you the total of all ratings, yes

sum is equivalent to reduce(_ + _), or fold(0)(_ + _)

Dominic Egger

@GrafBlutwurst

I think .sum etc exits for all T : Numeric

Sorixelle

@Sorixelle

where fold can be either foldLeft or foldRight

Dominic Egger

@GrafBlutwurst

with the ususal caveat on reduce of empty maps :D

ethicalbeginner

@nitishram

@AmirSarvestani i loaded the xml how to parse and get root and chile elements

RoelofWobben

@RoelofWobben

oke, so it looks like to me reduce does the same as folds for non-empty lists

Thanks all

Sorixelle

@Sorixelle

reduce is a fold with the head as the accumulator, and the tail as the list to fold over

ethicalbeginner

@nitishram

which is best method to parse large xml of size more than 2gb in scala/spark

Otto Chrons

@ochrons

a SAX parser?

Dominic Egger

@GrafBlutwurst

@RoelofWobben one small thing I'd prefer list.foldLeft(Option.empty[Int]) over Int.MaxValue because I find it cleaner in the case of an empty list. but that's just opinion

Sorixelle

@Sorixelle

While I'm here, quick question:

def apply(xs: String*) = // bla bla bla
implicit class StringOps(val s: String) extends AnyVal {
  // bla bla bla
}

Is there a way to make the StringOps apply in the definition of the apply method?

Dominic Egger

@GrafBlutwurst

doesn't it in eg xs.map( s => s.blah) ?

Sorixelle

@Sorixelle

I mean in val whatever = Foo(/* here */)

given apply is defined in Foo

ethicalbeginner

@nitishram

@ochrons yes

Sorixelle

@Sorixelle

I could import the implicit class, but I'd rather not have to if possible

because everything in that StringOps is only meant to be used in apply

Dominic Egger

@GrafBlutwurst

I don't think so but I'm not sure

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