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SCALA QUESTIONS

Going from local to remote actor messaging in AKKA
Going from local to remote actor messaging in AKKA
it should still fix some issue Remoting does not mean you automatically get actors distributed across the nodes, so creating a local actor is still a local actor, and an ActorRef to it will still be a local actor ref. What it gives you is the ability
TAG : scala
Date : November 28 2020, 09:01 AM , By : Jackiewu
How to make Mockito verify work with Enumeration
How to make Mockito verify work with Enumeration
Hope this helps I have following error in a unit test: , Your second enum should be using values instead of method definition:
TAG : scala
Date : November 28 2020, 09:01 AM , By : NideXTC
Akka model supervision
Akka model supervision
This might help you I have a problem with managing supervision. , The message is available in preRestart.
TAG : scala
Date : November 27 2020, 09:01 AM , By : Alexandr Zernov
Unit test for Scala object (not class)
Unit test for Scala object (not class)
To fix the issue you can do The short answer - You shouldn't unit-test singletons.The long is here - Unit testing with singletons.
TAG : scala
Date : November 27 2020, 09:01 AM , By : Jacob Sznajdman
Getting the element from a 1-element Scala collection
Getting the element from a 1-element Scala collection
I wish this help you Learning Scala and I keep wanting an equivalent to LINQ's Single() method. Example, , I'd use something more verbose instead of single:
TAG : scala
Date : November 27 2020, 09:01 AM , By : Nazar Maksymiv
Spark - Reduce with division operator
Spark - Reduce with division operator
wish helps you As far as I understand your intentions you should use join not an union
TAG : scala
Date : November 26 2020, 09:01 AM , By : Kazim Raza
SBT - "No Scala version specified or detected" using mirrored repository behind firewall
SBT - "No Scala version specified or detected" using mirrored repository behind firewall
I hope this helps you . I found the solution to my problem. My repositories file did not correctly point to an Ivy repository. Once I fixed it, everything worked like a charm.This is what my repositories file looks like now:
TAG : scala
Date : November 26 2020, 09:01 AM , By : soren
How do you get values for settings from a build.sbt file
How do you get values for settings from a build.sbt file
Hope that helps Just use .value method for properties and macros magic would do the work. See for example:
TAG : scala
Date : November 26 2020, 09:01 AM , By : Asus Gupta
Play too many arguments for method Apply
Play too many arguments for method Apply
this will help I am doing a Play2 and Scala tutorial from Pluralsight. , Parameter list that you declared in your view is wrong
TAG : scala
Date : November 25 2020, 09:00 AM , By : Juan Diego Lara
How to solve transitive dependencies version conflicts (scala/sbt)
How to solve transitive dependencies version conflicts (scala/sbt)
should help you out This is classic Jar Hell, and it is a problem on any JVM based project not just scala with sbt.There are 4 common solutions
TAG : scala
Date : November 23 2020, 09:01 AM , By : Shubham Shah
Writing DataFrame to MemSQL Table in Spark
Writing DataFrame to MemSQL Table in Spark
it should still fix some issue Try using createMemSQLTableAs instead of saveToMemSQL.saveToMemSQL loads a dataframe into an existing table, where as createMemSQLTableAs creates the table and then loads it. It also returns a handy dataframe wrapping t
TAG : scala
Date : November 22 2020, 02:42 PM , By : Garb
How to add columns into org.apache.spark.sql.Row inside of mapPartitions
How to add columns into org.apache.spark.sql.Row inside of mapPartitions
To fix this issue Usually there should be no need for that and it is better to use UDFs but here you are:
TAG : scala
Date : November 22 2020, 02:42 PM , By : Manuel Quesada Moren
Set Play Framework Environment
Set Play Framework Environment
will help you As I understand it, what you observe is the correct behavior of Play 2.4In dev mode, 404 are handled by the devNotFound.scala.html template and yield errors which look like :
TAG : scala
Date : November 22 2020, 09:00 AM , By : Naive D Jack
Either[A, Future[B]] to Future[Either[A, B]]
Either[A, Future[B]] to Future[Either[A, B]]
wish helps you Not sure there's an out of the box solution, this is what I came up with:
TAG : scala
Date : November 22 2020, 09:00 AM , By : Bradley
store a bunch of configuration information in scala
store a bunch of configuration information in scala
help you fix your problem Typesafe Config is a good library for what you seek. It allows you to store your config in HOCON (a JSON superset).If you choose this solution, you can also check out Ficus, which provides a nice Scala wrapper.
TAG : scala
Date : November 22 2020, 09:00 AM , By : DrDew00
Spark: How to transform LabeledPoint features values from int to 0/1?
Spark: How to transform LabeledPoint features values from int to 0/1?
With these it helps I want to run Naive Bayes in Spark, but to do this I have to transform features values from my LabeledPoint to 0/1. My LabeledPoint looks like this: , I guess you're looking for something like this:
TAG : scala
Date : November 22 2020, 09:00 AM , By : m3ta
How to get input from Scala after a certain point in time?
How to get input from Scala after a certain point in time?
To fix this issue There's no standard way of clearing stdin with Scala's (or even Java's) API.You can use this lower-level implementation RawConsoleInput to clear the buffer though.
TAG : scala
Date : November 21 2020, 07:38 AM , By : Agboola Niyi
Where do I put my tests when I split my Play project into sub modules
Where do I put my tests when I split my Play project into sub modules
This might help you If your tests not gets executed by test command, probably your project not configured correctly. Normally multi project sbt aggregates subprojects:
TAG : scala
Date : November 21 2020, 07:38 AM , By : Nada Ellahony
Read Array in sub queries spark sql using scala
Read Array in sub queries spark sql using scala
fixed the issue. Will look into that further I'm trying to achieve this query using scala in spark sql , i got the answer
TAG : scala
Date : November 20 2020, 09:01 AM , By : Samir Hassen
Scala map with implicit conversion
Scala map with implicit conversion
Hope this helps You need to put the type annotation in a different place: routeScala.shape.map(p => p: Position). But I'd say this is less clear than just writing routeScala.shape.map(PositionScala.toJava).
TAG : scala
Date : November 19 2020, 03:54 PM , By : Jeff K
Spark, Scala, DataFrame: create feature vectors
Spark, Scala, DataFrame: create feature vectors
like below fixes the issue I have a DataFrame that looks like follow: , Suppose:
TAG : scala
Date : November 19 2020, 12:35 AM , By : Christopher Hernande
Scala Enumeration: Choose some values as type
Scala Enumeration: Choose some values as type
it should still fix some issue Just googled "Scala enumerations", and clicked on the second link. In a nutshell, this quotes Martin Odersky who says that enums are meant as simple integer constants with names and an order. If you want types, you shou
TAG : scala
Date : November 18 2020, 09:01 AM , By : raj
How can I create a Spark DataFrame from a nested array of struct element?
How can I create a Spark DataFrame from a nested array of struct element?
seems to work fine One possible way to handle this is to extract required information from the schema. Lets start with some dummy data:
TAG : scala
Date : November 17 2020, 09:01 AM , By : Shaahin h
why scala lambda with _ can't using && to combine two bool expression
why scala lambda with _ can't using && to combine two bool expression
This might help you You can think of the place holder as being matched with the lambda's arguments positionnally. The first occurrence of the _ is matched with the first argument, the second occurence is matched with the second argument, etc.
TAG : scala
Date : November 16 2020, 09:01 AM , By : Harsha Reddy
Return elements from array, except for repeating
Return elements from array, except for repeating
wish help you to fix your issue Write a method that returns the values of all elements in the array, except for repeating. Do not use for. - this is task from Scala book. , Set contains unique value, so use conversion to it:
TAG : scala
Date : November 14 2020, 09:01 AM , By : MANOJ KUMAR
Heroku: deploy Spray based service
Heroku: deploy Spray based service
seems to work fine The Procfile must exist in the root directory of the Git repo. The commands in the Procfile must also be relative to the root dir (which will be the current working dir when heroku runs it).
TAG : scala
Date : November 14 2020, 07:01 AM , By : Ulises Martinez
Mass-add an object if it is an instance of a class
Mass-add an object if it is an instance of a class
I wish did fix the issue. Using pattern matching, as Archeg mentions, is already much better. But for this case you might also consider reflection:
TAG : scala
Date : November 14 2020, 07:01 AM , By : White Wolf Spirits
Automatically convert a case class to an extensible record in shapeless?
Automatically convert a case class to an extensible record in shapeless?
help you fix your problem If I have these two case classes: , Suppose we've got the following setup:
TAG : scala
Date : November 14 2020, 06:58 AM , By : Mike Langley
How to use pipeTo in AKKA correctly
How to use pipeTo in AKKA correctly
wish help you to fix your issue They are the same. The sender is not going to change. pipeTo takes its argument by value, not by name.
TAG : scala
Date : November 14 2020, 06:58 AM , By : Andrea Lluch Cruz
Define a common trait for types with different numbers of type parameters
Define a common trait for types with different numbers of type parameters
will be helpful for those in need You can make the MapR trait have a type member with a single type parameter than can alias the Generic traits on implementation. This would require each Generic trait to describe how it is parameterized.
TAG : scala
Date : November 13 2020, 09:01 AM , By : Qing Zhou
RDD Persistence in Spark
RDD Persistence in Spark
seems to work fine If i do another transformation or action to this rdd, will this persistance stop exist
TAG : scala
Date : November 12 2020, 09:01 AM , By : RavenDark
Scala trait as a method input - type mismatch error
Scala trait as a method input - type mismatch error
will help you I wrote a method that gets a trait type as an input. This is the trait Localizable: , Your problem is that here:
TAG : scala
Date : November 12 2020, 09:01 AM , By : Jon Reader
Scala compiler optimization for immutability
Scala compiler optimization for immutability
help you fix your problem First of all: the actual freeing of unused memory happens whenever the JVM GC deems it necessary. So there is nothing scalac can do about this.The only thing that scalac could do would be to set references to null not just w
TAG : scala
Date : November 12 2020, 09:01 AM , By : Vinaykumar N H
Base class reference in Scala
Base class reference in Scala
may help you . In Scala, as in Java, array and list does not store actual elements, they only store references to actual elements(non primitives). That means you can do same thing with arrays.Java arrays do store some actual elements of primitive dat
TAG : scala
Date : November 11 2020, 09:01 AM , By : Clive Grant
Akka: The order of responses
Akka: The order of responses
I think the issue was by ths following , My demo app is simple. Here is an actor: , normal behavior?Yes, this is absolutely normal behavior.
TAG : scala
Date : November 09 2020, 09:01 AM , By : Mwesigwa Denis
Why does enablePlugins(DockerPlugin) from sbt-docker in Play project give "error: reference to DockerPlugin is ambi
Why does enablePlugins(DockerPlugin) from sbt-docker in Play project give "error: reference to DockerPlugin is ambi
I hope this helps . As the message says "and import _root_.com.typesafe.sbt.packager.docker.DockerPlugin" sbt-native-packager comes with the conflicting DockerPlugin class. But that's what you know already.The trick is that the Play plugin depends on
TAG : scala
Date : November 09 2020, 08:00 AM , By : hayk harutyunyan
Convert a scala list of Strings into a list of Doubles while discarding unconvertable strings
Convert a scala list of Strings into a list of Doubles while discarding unconvertable strings
hop of those help? I'm trying to parse a list of strings into a numeric format, while ignoring anything that can't be parsed. This is my attempt, but I can't help but think it's a common enough pattern that there must be a better way than having to c
TAG : scala
Date : November 09 2020, 08:00 AM , By : Wern
Change the contents of a file in scala
Change the contents of a file in scala
hope this fix your issue Save to a different file and rename it back to original one. Use if-else This should work:
TAG : scala
Date : November 08 2020, 09:00 AM , By : Apoorv Prasad
Akka Actor testing with ScalaTest using Testkit EventListeners
Akka Actor testing with ScalaTest using Testkit EventListeners
This might help you Since you made afterAll a val it is evaluated on construction and the actor system is shutdown before the tests are run. Change it to a method (def) and it will work.
TAG : scala
Date : November 07 2020, 01:33 PM , By : Thiago Alves
Prepare data for MultilayerPerceptronClassifier in scala
Prepare data for MultilayerPerceptronClassifier in scala
With these it helps The source of your problems is a wrong definition of layers. When you use
TAG : scala
Date : November 07 2020, 01:32 PM , By : Vinícius Silva
Immutability and custom deserialization in Scala
Immutability and custom deserialization in Scala
fixed the issue. Will look into that further One word: reflection. In particular, Java reflection. Java reflection doesn't know anything about Scala's semantics, so it will happily let you do things that are forbidden in Scala. In fact, Java's reflec
TAG : scala
Date : November 07 2020, 01:32 PM , By : orangeb
Play Framework dependency injection Object vs @Singleton Class
Play Framework dependency injection Object vs @Singleton Class
it fixes the issue I can see three advantages of using @Singleton class over object if A has no dependencies:
TAG : scala
Date : November 07 2020, 01:32 PM , By : Rastimir Orlic
Slick 3 transaction how to
Slick 3 transaction how to
I think the issue was by ths following , Trying to wrap my head around the slick 3 api. , transactionally is function of DBIO, try this:
TAG : scala
Date : November 07 2020, 01:32 PM , By : Ana Docampo
When should avoid usage of Future in scala
When should avoid usage of Future in scala
wish helps you There is no need to 'futurise' anything unless that method has asynchronous work to do, i.e. has to wait itself for futures. If the method takes too much time, the caller can always wrap the call into a Future. I would therefore conclu
TAG : scala
Date : November 07 2020, 09:00 AM , By : Shashank Chouksey
Which Spark operation returns the elements not matched by a join?
Which Spark operation returns the elements not matched by a join?
I hope this helps you . Instead of a join , you can do fullOutterJoin, and filter the values that are None on Either sidefrom the documentation:
TAG : scala
Date : November 06 2020, 09:01 AM , By : pinkette
How to group incoming events from infinite stream?
How to group incoming events from infinite stream?
this one helps. I came up with a somewhat gnarly solution but I think it gets the job done. The essential idea is to use the keepAlive method of Source as the timer that will trigger completion.
TAG : scala
Date : November 06 2020, 09:01 AM , By : WeirdThinker15
Converting a List to a Case Class
Converting a List to a Case Class
should help you out This can be done very straightforwardly using shapeless's Generic and FromTraversable type classes,
TAG : scala
Date : November 06 2020, 04:03 AM , By : nicholas matthews
Get names of the variables in an object
Get names of the variables in an object
wish help you to fix your issue consider the following object:
TAG : scala
Date : November 06 2020, 03:59 AM , By : bob_ye
Generics re: Scala.math.Ordering wrapper instance for java.lang.Comparable
Generics re: Scala.math.Ordering wrapper instance for java.lang.Comparable
Does that help The standard library already provides these instances via Ordering.ordered. For example, if you have a class like this:
TAG : scala
Date : November 04 2020, 04:02 PM , By : Aman Singhaniya
implicit Impl method for collections in scala breeze
implicit Impl method for collections in scala breeze
will be helpful for those in need The docs could be much better for this, and I do wish I could make the error messages more helpful.If you look at stddev's source you'll see that it requires an implementation of variance.Impl, which requires a meanA
TAG : scala
Date : November 04 2020, 04:00 PM , By : Tomek Dabrowski
How to have colored REPL for 'sbt console'?
How to have colored REPL for 'sbt console'?
should help you out From Scala 2.11.4 onwards you can get a colored REPL by invoking scala -Dscala.color. My question is whether it is possible to get the same colored REPL when I call sbt console within my SBT project? , Put this into your ~/.sbt/0.
TAG : scala
Date : November 04 2020, 09:01 AM , By : 郭咳咳
Using the squants library, how do I specify a specific unit of measure for a method?
Using the squants library, how do I specify a specific unit of measure for a method?
Hope this helps I went through the same process and this is what I found: The squants library, at least by itself, will not give you exactly what you're looking for. The typesafety it provides, refers specifically to not mixing different types of qua
TAG : scala
Date : November 04 2020, 09:01 AM , By : Varien Janitra
Play Framework: Gzip compression/decompression of data over WebSocket
Play Framework: Gzip compression/decompression of data over WebSocket
With these it helps AFAIK there is some compression extension for websocket connections. (http://tools.ietf.org/html/draft-tyoshino-hybi-permessage-compression-00).In some browsers this should be fixed by now and enabled by default (Chrome). In other
TAG : scala
Date : November 04 2020, 09:01 AM , By : Mojtaba Hosseinzadeh
Why does mapPartitions print nothing to stdout?
Why does mapPartitions print nothing to stdout?
Hope that helps mapPartitions is a transformation, and thus lazyIf you will add an action in the end, the whole expression will be evaluated. Try adding s.count in the end.
TAG : scala
Date : November 04 2020, 08:17 AM , By : Will Scott
Call doAnswer with function as argument in scala play 2.4
Call doAnswer with function as argument in scala play 2.4
To fix the issue you can do Which version of specs2 are you using? With 3.6.5 (the latest) the following works fine
TAG : scala
Date : November 04 2020, 08:17 AM , By : Pavan D
Get or create child actor by ID
Get or create child actor by ID
Hope this helps Determining the existence of an actor cannot be done synchronously. So you have a couple of choices. The first two are more conceptual in nature to illustrate doing asynchronous lookups, but I offer them more for reference about the a
TAG : scala
Date : November 04 2020, 08:17 AM , By : Shashikant Shrivas
Why substracting two Dates gives me an extra hour?
Why substracting two Dates gives me an extra hour?
This might help you You are constructing a Date object using the time delta between clock measurements. Therefore the SimpleDateFormat is translating the Date to local time when constructing the String. From the documentation (emphasis mine):
TAG : scala
Date : November 03 2020, 09:01 AM , By : Steve Goodman
Akka, advices on implementation
Akka, advices on implementation
hope this fix your issue For time based activity, i.e. "ticks" or "heartbeats", the documentation demonstrates a very good pattern for sending messages to Actors periodically.For your other need, Actors responding to messages as they come in, this is
TAG : scala
Date : November 03 2020, 09:01 AM , By : Azriel K
Spark Scala 2.10 tuple limit
Spark Scala 2.10 tuple limit
Hope this helps If all you do is modifying values from an existing DataFrame it is better to use an UDF instead of mapping over a RDD:
TAG : scala
Date : November 02 2020, 09:01 AM , By : monxoom
Scala currying and type inference
Scala currying and type inference
Hope this helps This is intended. If it were allowed (some languages really allow that), that would make it work when you forget to put an argument, and instead of compile-time error you would expect. This happens so often that scala authors decide t
TAG : scala
Date : November 01 2020, 04:09 PM , By : Elizabeth Garbee

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