scala

问题 I wanted to append a dataframe to another empty dataframe in a loop and finally write to a Location. My Code - val myMap = Map(1001 -> "rollNo='12'",1002 -> "rollNo='13'") val myHiveTableData = spark.table(<table_name>) val allOtherIngestedData = spark.createDataFrame(sc.emptyRDD[Row],rawDataHiveDf.schema) myMap.keys.foreach { i => val filteredDataDf = myHiveTableData.where(myMap(i)) val othersDf = myHiveTableData.except(filteredDataDf) allOtherIngestedData.union(othersDf) filteredDataDf

问题 I'm writing a macro called assign whose job is to assign values from members of one instance to another with a particular prefix added to the name of the member. For example, I have an instance with members named my_prefix_data, my_prefix_rden, ... and I want to assign values to these members from another instance with corresponding members named data, rden, ... . I've made a prototype version of the macro that just handles the my_prefix_data <- data assignment. The assignments are to be made

问题 I use rampUsers(20)over (120) in my gatling load test. But I got the following result I expected the active user should be constant during the test. 回答1: rampUsers injects the defined numbers of users linearly over a given time. So your use of rampUsers(20)over (120) will result in gatling starting one user every 6 seconds. The graph you're getting shows this, but what might be confusing is that since your scenario completes in less than 6 seconds there's never more than one user active at a

问题 I have a customized compare methods that takes two parameters. One of them are expected to be implicitly convertible to another: object Test extends App { def compare[T1, T2](a: T1, b: T2)(implicit ev: T1 => T2) = compareImpl[T2](ev(a), b) def compare[T1, T2](a: T1, b: T2)(implicit ev: T2 => T1) = compareImpl[T1](a, ev(b)) def compareImpl[T](a: T, b: T) = a == b case class Foo(s: String) case class Bar(s: String) implicit def foo2bar(f: Foo): Bar = Bar(f.s) println(compare(Foo("hello"), Bar(

问题 I learn scala in university and I cannot understand how to use map, flatmap and Option. Here's couple functions from my lab. I know how to implement first but I have no idea how to deal with second? So, the question: how to implement second function without changing it's signature (using map and flatmap)? def testCompose[A, B, C, D](f: A => B) (g: B => C) (h: C => D): A => D = h compose g compose f def testMapFlatMap[A, B, C, D](f: A => Option[B]) (g: B => Option[C]) (h: C => D): Option[A] =>

问题 I'm having problems joining 2 kafka streams extracting the date from the fields of my event. The join is working fine when I do not define a custom TimeStampExtractor but when I do the join does not work anymore. My topology is quite simple: val builder = new StreamsBuilder() val couponConsumedWith = Consumed.`with`(Serdes.String(), getAvroCouponSerde(schemaRegistryHost, schemaRegistryPort)) val couponStream: KStream[String, Coupon] = builder.stream(couponInputTopic, couponConsumedWith) val

问题 Assuming that a class Thing is defined, and an operation + is associated with a type class: trait TypeClass[X, Y] { type Out def v: Out } object TypeClass { implicit def summon[X <: Int, Y <: Int]: TypeClass[X, Y] = new TypeClass[X, Y] { type Out = Int override def v: Out = 2 } } case class Thing[X]() { def +[Y](that: Thing[Y])(implicit typeClass: TypeClass[X, Y]): typeClass.Out = typeClass.v } Now if I want to define a shortcut function +2x , which represents X + Y + Y . My first instinct

问题 Following the tutorial at: https://github.com/julienrf/lms-tutorial/wiki I have succesfully compiled and understood most of the code. While the concepts and examples are extremely sexy, i immediately wanted to change the code from hard-coding "Double" as the set of scalars into anything implementing the type-class Numeric[T] from the standard library. I was, however, unsuccessful. I tried things like adding the following code to the LinearAlgebraExp trait: override type Scalar = Double

问题 I have a sbt config with scala play! server, a scalajs client, and shared project which contains classes which are passed between the two. I want my client to have strong type information for the server API calls so I'm writing a task that for each route in the routes file builds a corresponding method in the client. I have a prototype that is able to parse almost all of the information I need out of the routes file. The only thing I can't get is return types. Here's what I have so far (I

问题 I have the following .check on my returned body: (I changed the values for security reasons but the structure is the same) .exec(http("Get ids") .post("GetIds") .body(ElFileBody("json/getIds.json")).asJson .check(jsonPath("$...Types..[?(@.Type == 'web')].id").findAll.saveAs("IDLlist")) But the transaction fails with "Gettting findAll.exists extraction crashed: end of input expected when trying to extract values from a returned body" Gatling prints the body of the failed transaction, when I