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SCALA QUESTIONS

Scala Named method arguments cannot resolve symbol
Scala Named method arguments cannot resolve symbol
Any of those help Scala 2.12 supports named parameters for Java if they are available, but by default Java is compiled without storing parameter names. So most Java libraries don't have them (because the benefit in Java itself is minimal), including
TAG : scala
Date : November 25 2020, 04:01 AM , By : Sethulakshmi V Meppa
ScalaTest: treat Instants as equal when in the same millisecond
ScalaTest: treat Instants as equal when in the same millisecond
should help you out We use Clock.instant to know the current time instead of Instant.now to avoid this problem. So the code for the class should be this way
TAG : scala
Date : November 25 2020, 04:01 AM , By : user2186600
how to iterate a list to create to Map?
how to iterate a list to create to Map?
I wish this help you If you really need to iterate only once and build map's on fly, you can do it with foldLeft:
TAG : scala
Date : November 22 2020, 04:01 AM , By : Nkwoji Obinna
Debugging a filter operation in scala through `in-code variable inspection`
Debugging a filter operation in scala through `in-code variable inspection`
help you fix your problem The problem is that you assigned boolean result of method contains to a val inspectVariable. This operation has a return type of Unit. But filter method requires boolean. Just remove val inspectVariable = and this should fix
TAG : scala
Date : November 22 2020, 04:01 AM , By : user2185646
why it raise a error when rdd use sortby with ordering
why it raise a error when rdd use sortby with ordering
I wish this help you if you see the signature of method sortBy, you will see it needs 2 parameters Ordering and ClassTag. you need to send the class tag of your Tuple
TAG : scala
Date : November 22 2020, 04:01 AM , By : user2185504
Scala Future.find
Scala Future.find
hop of those help? You're right that the deprecated Future.find which expects a TraversableOnce[Future[T]] in 2.12.x does behave differently from the replacing Future.find. As you can see from the pasted source code below, the former find method util
TAG : scala
Date : November 21 2020, 04:01 AM , By : user2185303
Functional Programming: Get new Map from existing Map with changed value
Functional Programming: Get new Map from existing Map with changed value
wish of those help I have one map like , Why not simply use,
TAG : scala
Date : November 20 2020, 04:01 AM , By : 圣光七仔
What are the uses of implicits and How to use them in scala?
What are the uses of implicits and How to use them in scala?
hope this fix your issue I am answering this question more from the perspective of "what are the uses of implicits (why are implicit required in some situations)" instead of "how to use implicit in some of these situations" (as answer to this can be
TAG : scala
Date : November 20 2020, 04:01 AM , By : user2184884
CPS style for linked-list style function calls
CPS style for linked-list style function calls
Hope this helps It looks like you construct a singly-linked list of Foo values; new values are added at the end of the list as long as the signum of the new value is different than an existing value.In a functional approach, you wouldn't embed list m
TAG : scala
Date : November 19 2020, 04:01 AM , By : user2184555
need help in finding sbt assembly
need help in finding sbt assembly
like below fixes the issue Please look at the below link to find the available versions of abt-assembly.https://bintray.com/eed3si9n/sbt-plugins/sbt-assembly
TAG : scala
Date : November 19 2020, 04:01 AM , By : user2184547
how to cast a spark row(StructType) to scala case class
how to cast a spark row(StructType) to scala case class
it should still fix some issue The problem is that .as on Row does just a typecast nothing else. the internal type of trips is actually Rowso row.getAs[WrappedArray[Row]]("trips") will work. then you can map over it and construct myRow from Row.
TAG : scala
Date : November 18 2020, 04:01 AM , By : Fredrik Pettersson
Subtract days from a date in the form of a string
Subtract days from a date in the form of a string
help you fix your problem I have a date in the form of a string like below , You need the formatter for both parsing and formatting for output.
TAG : scala
Date : November 17 2020, 04:01 AM , By : user2183790
How to find common elements among two array columns?
How to find common elements among two array columns?
wish of those help Based on SCouto answer, I give you the complete solution that worked for me:
TAG : scala
Date : November 16 2020, 04:01 AM , By : Skean66
How to read multiline json with root element in Spark Scala?
How to read multiline json with root element in Spark Scala?
Hope that helps This is a Sample JSON file. I want to do it generally, like if I have root tags then how can I read the JSON data into Dataframe and print in the console. , Try that:
TAG : scala
Date : November 14 2020, 04:01 AM , By : user2182969
Scala - why cannot use trait from object
Scala - why cannot use trait from object
seems to work fine I have created a simple application with singleton object which contains local traits: , It's a trait so you'll need to "instantiate" it properly:
TAG : scala
Date : November 13 2020, 04:01 AM , By : user2182639
Change metastore URI in Spark
Change metastore URI in Spark
With these it helps Finally, after I was reviewing the configuration of the sqlContext variable that spark-shell creates automatically in the server, I have seen that there a lot of url's and configuration variables and that I don't have permissions
TAG : scala
Date : November 13 2020, 04:01 AM , By : Islon
Evolution of kafka-streams topology in production
Evolution of kafka-streams topology in production
To fix the issue you can do At the moment, there is no checkpointing or savepoint type concept in Kafka Streams.If you need to update the existing applications, it is safe to use the new application.id or reset the existing application.id.
TAG : scala
Date : November 11 2020, 04:01 AM , By : user2181725
How to regroup several files into one?
How to regroup several files into one?
this will help you didn't specify anything about the original file formats so assuming you've got them in dataframes f1,f2... you can create a unified dataframe by joining them val unified=f1.join(f2,f1("id")===f2("id")).join(f3, f1("id")===f3("id"))
TAG : scala
Date : November 11 2020, 04:01 AM , By : Nabil Affandi
When to use "sbt assembly" and "sbt compile && sbt package"?
When to use "sbt assembly" and "sbt compile && sbt package"?
hope this fix your issue I would like to know when should I use sbt assembly and when sbt compile sbt package?
TAG : scala
Date : November 11 2020, 04:01 AM , By : user2181618
Where is the implicit value for parameter P: cats.Parallel[cats.effect.IO,F]
Where is the implicit value for parameter P: cats.Parallel[cats.effect.IO,F]
I hope this helps you . The implicit you're looking for is defined in cats.effect.IOInstances and you can bring it in scope by importing cats.effect.IO._.
TAG : scala
Date : November 10 2020, 04:01 AM , By : Ayman shawhy
functional programming: Get list of data from nested loop
functional programming: Get list of data from nested loop
fixed the issue. Will look into that further I have three class , With a for-comprehension:
TAG : scala
Date : November 10 2020, 04:01 AM , By : Bug Smasher
Scala, generic tuple
Scala, generic tuple
hop of those help? It's a little bit unsafe but you can use Structural type in this case:
TAG : scala
Date : November 07 2020, 04:01 AM , By : origamimadness
How to remove found :AnyVal required :Double in scala ?
How to remove found :AnyVal required :Double in scala ?
this will help Welcome to SO.The problem you are experiencing is due to the fact that you are providing an Int as a default value when the key is not found in your Map, instead of a Double. If you change 0 by 0.0 or 0D it should work. i.e
TAG : scala
Date : November 07 2020, 04:01 AM , By : unknown
Hellinger Distance in Scala
Hellinger Distance in Scala
this will help Given 2 Array[Double] which contains discrete probability distributions, how do I implement the Hellinger Distance in Scala? , Below is just the mathematical formula in scala code:
TAG : scala
Date : November 07 2020, 04:01 AM , By : naam
Scala chaining functions when Some without explicit checks
Scala chaining functions when Some without explicit checks
Hope this helps I'm trying to find a proper way of executing chained functions, as long as Some is returned. Returning None should stop executing further. I believe there must be a way of doing it without checks inside each of the function. A simple
TAG : scala
Date : November 06 2020, 04:01 AM , By : user2180160
How to head DataFrame with Map[String,Long] column and preserve types?
How to head DataFrame with Map[String,Long] column and preserve types?
should help you out The type problem is easy to solve, by explicitly specifying the type parameters at the source which is getMap(14). Since you know that the you are expecting a Map of String -> Int key-value pairs, just replace getMap(14) by getMap
TAG : scala
Date : November 06 2020, 04:01 AM , By : Mackulan55
How to work Supervision strategy after recover at non-linear graphs in Akka Streams
How to work Supervision strategy after recover at non-linear graphs in Akka Streams
I hope this helps . First, let's add a couple of print statements to more clearly see what's going on: one at the completion of the stream...
TAG : scala
Date : November 06 2020, 04:01 AM , By : starshi
Spark streaming from kafka topic using scala
Spark streaming from kafka topic using scala
I wish this help you This issue is related to library versions. I have just updated my build.sbt like this
TAG : scala
Date : November 06 2020, 04:01 AM , By : Pall Eniko
Scala concatenate Column of Array[String] into single Array[String]
Scala concatenate Column of Array[String] into single Array[String]
this will help You need to explode the token column take the count after grouping by the individual tokens:
TAG : scala
Date : November 05 2020, 04:01 AM , By : schbeb
How to find a string in a list of case class
How to find a string in a list of case class
Hope that helps I have a case class Color , How about
TAG : scala
Date : November 04 2020, 04:01 AM , By : Denys Lins
Why would trait's val be evaluated if it is overridden in class?
Why would trait's val be evaluated if it is overridden in class?
will help you As described in this Scala doc:
TAG : scala
Date : November 04 2020, 04:01 AM , By : user2179262
SBT confused about Scala types
SBT confused about Scala types
I hope this helps you . The issue is that the filter method is added to arrays via an implicit. When you call args.filter(...), args is converted to ArrayOps via the Predef.refArrayOps implicit method.You are defining a implicit conversion from Array
TAG : scala
Date : November 02 2020, 04:01 AM , By : Ronald Barboza
Scala Cats: How do I convert a List[ValidatedNel[E, A]] to Ior[NonEmptyList[E], List[A]]?
Scala Cats: How do I convert a List[ValidatedNel[E, A]] to Ior[NonEmptyList[E], List[A]]?
Does that help I tried: , As @Toxaris mentioned, -Ypartial-unification needed to be toggled on
TAG : scala
Date : November 02 2020, 04:01 AM , By : ramesh
Is there an elegant way in Scala to define an asynchronous API based on a synchronous one?
Is there an elegant way in Scala to define an asynchronous API based on a synchronous one?
hope this fix your issue If the synchronous api is defined by you, you could write the following:
TAG : scala
Date : November 02 2020, 04:01 AM , By : Millhouse17
Slick - How to insert into table with no primaryKeys
Slick - How to insert into table with no primaryKeys
around this issue I have a table with no primary keys. How can I insert data into it. When I have a table with primary key I can do insertOrUpdate(...) but I don't see a method for just inserting. , You can resort to using += to insert a row:
TAG : scala
Date : November 01 2020, 04:01 AM , By : user2178350
how to convert string to int - 0 when string is empty
how to convert string to int - 0 when string is empty
hope this fix your issue You want to use String.toInt() as you know that you have something that is convertible to int :
TAG : scala
Date : November 01 2020, 04:01 AM , By : kv.vinay kumar
Retrieving list of objects from application.conf
Retrieving list of objects from application.conf
wish helps you I have the following entry in Play for Scala application.conf: , Try this one:
TAG : scala
Date : November 01 2020, 04:01 AM , By : endlessme
Cats Effect IO: Compose IO with Scala collections
Cats Effect IO: Compose IO with Scala collections
Hope this helps Your for comprehension is for your IO, but you're mixing it with List. To make it a bit clearer we can expand the for comprehension, which won't compile for the same reason that you can't flatten a List into an IO:
TAG : scala
Date : October 31 2020, 05:01 AM , By : user2178082
Scala foldLeft while some conditions are true
Scala foldLeft while some conditions are true
I think the issue was by ths following , First, note that your example seems wrong. If I understand correctly what you describe, the result should be 1 (the last value on which the predicate _ < 3 was satisfied), not 6The simplest way to do this is u
TAG : scala
Date : October 30 2020, 05:01 AM , By : user2177624
Alpakka kafka vs Kafka streams
Alpakka kafka vs Kafka streams
seems to work fine The key difference is that Kafka streams require Kafka topics on the input side and on the output side. With Alpakka you can create processing pipeline for all kind of inputs and outputs not only Kafka topics. Also, akka streams DS
TAG : scala
Date : October 29 2020, 05:01 AM , By : Subin
What is the proper way to compute graph diameter in GraphX
What is the proper way to compute graph diameter in GraphX
To fix this issue GraphX actually has no notion of direction it you don't tell it to use it. If you look at the inner workings of the ShortestPaths library you'll see that it uses Pregel and the direction is default (EdgeDirection.Either). This means
TAG : scala
Date : October 29 2020, 05:01 AM , By : user2177380
Scala: Chaining futures, returning the first
Scala: Chaining futures, returning the first
hope this fix your issue flatMap is your friend. You can just use a for-comprehension + recover:
TAG : scala
Date : October 29 2020, 05:01 AM , By : JMeys
Akka. How to set a pem certificate in a https request
Akka. How to set a pem certificate in a https request
it fixes the issue The following allows making a https request and identifying yourself with a private key from a x.509 certificate.The following libraries are used to manage ssl configuration and to make https calls:
TAG : scala
Date : October 29 2020, 05:01 AM , By : user2177316
Flink: Access Key in RichMapFunction applied on KeyedStream to handle stream keyed by Option
Flink: Access Key in RichMapFunction applied on KeyedStream to handle stream keyed by Option
will help you It's not supported for now. The key can be aquired by getCurrentKey() method in KeyContext class, which is not exposed in RichMapFunction. However, Flink internally provides the KeyedProcessFunction that can return key in the parameter
TAG : scala
Date : October 29 2020, 05:01 AM , By : Emre Kaya
Usage of state in updateState method (Persistent Actor)
Usage of state in updateState method (Persistent Actor)
With these it helps From Akka Cookbook, example from chapter Persistent Actors. In SamplePersistentActor.scala there is line of code that I don't quite understand. Here's the full code of 2 files. , In your sample code:
TAG : scala
Date : October 28 2020, 07:40 AM , By : Revathi Balusamy
Scala 2.8 - Potential problem with named arguments
Scala 2.8 - Potential problem with named arguments
I wish this help you The second code block does compile, provided you put something in place of the /* some code that gives integer */ placeholder comment.
TAG : scala
Date : October 23 2020, 11:12 PM , By : user56697
"using" function
"using" function
wish helps you Someone has already done this—it's called Scala ARM.From the readme:
TAG : scala
Date : October 14 2020, 11:12 PM , By : user3852485
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