A better way to test the value of an Option?
How about if (opt == Some(“lakes”)) This expresses the intent clearly and is straight forward.
scala
How to show scala doc from Java Editor in Eclipse?
When using maven convention, a library is bundled as ‘group.artifact.version.jar’ for binary, ‘group.artifact.version-sources.jar’ for source code and ‘group.artifact.version-javadoc.jar’ for docs. If you don’t see the javadoc, then it means that the ‘-javadoc.jar’ for that artifact is not pulled to local, in your case for the akka artifact. If you right click on the library, you … Read more
In ScalaTest is there any difference between `should`, `can`, `must`
should and must are the same semantically. But it’s not about better documentation, it’s basically just down to personal stylistic preference (I prefer must for example). can is a little different. You can’t (nomen omen) use it directly as a matcher, it’s only available in a test descriptor. Quote from FlatSpec: Note: you can use … Read more
When would I use the “Mark directory as …” option in IntelliJ IDEA?
Lets go through the options: Sources Root – this is where your actual project code goes – typically in src/main/scala (though you can change that, or add extra source directories in your build). Directories nested below this level should be packages. Intellij needs to know these are sources so it can highlight them, check them … Read more
How to access values in array column?
Since Spark 2.4.0, there is a new function element_at($array_column, $index). See Spark docs
Play Framework: How to serialize/deserialize an enumeration to/from JSON
implicit val genderReads = Reads.enumNameReads(Gender) is working fine for me. Play Scala 2.4.2
How do I access scala documentation from the repl?
Scaladocs are generated as HTML, so you don’t want them appearing in the REPL window. You might want to load docs in a browser from the REPL, however. You can do that by creating your own method like so (this one takes an instance; you could have it take an instance of Class[A] instead, if … Read more
Forward References – why does this code compile?
The body of a class or an object is the primary constructor. A constructor, like a method, is a sequence of statements that are executed in order — to do anything else, it would have to be a very different language. I’m pretty sure you wouldn’t like for Scala to execute the statements of your … Read more
Spark / Scala: forward fill with last observation
Initial answer (a single time series assumption): First of all try avoid window functions if you cannot provide PARTITION BY clause. It moves data to a single partition so most of the time it is simply not feasible. What you can do is to fill gaps on RDD using mapPartitionsWithIndex. Since you didn’t provide an … Read more
What does dollar sign do in scala
That isn’t special Scala syntax, it’s a method name. In Scala $ is a legal identifier. The method is inherited from the org.apache.spark.ml.param.Param trait. See the source.