scala

问题 I am using anorm to query and save elements into my postgres database. I have a json column which I want to read as class of my own. So for example if I have the following class case class Table(id: Long, name:String, myJsonColumn:Option[MyClass]) case class MyClass(site: Option[String], user:Option[String]) I am trying to write the following update: DB.withConnection { implicit conn => val updated = SQL( """UPDATE employee |SET name = {name}, my_json_column = {myClass} |WHERE id = {id} """

问题 I have a Java code calling Scala method. Java side code: List<String> contexts = Arrays.asList(initialContext); ContextMessage c = ContextMessage.load(contexts); Scala side code: def load(contexts: List[String]) = ... contexts foreach context => In this case, I have scala.collection.immutable.List<String> cannot be applied ... error message. I also need to make the type of contexts as general as possible (i.e., Seq) as the load method iterates over the given collection object to process

问题 Assuming if I have the following Record typed data, and a hlist of keys: val rr = ("a" ->> 1) :: ("b" -> "s") :: ("c" -> 3) :: HNil val hh = "c" :: "b" :: HNil And I want to extract values in rr for each key in hh , then combine them into a type level object, eventually yielding: (3: Int) :: ("s": String) :: HNil How this can be achieved with least amount of code? I could obviously write a inductively-summoned implicit function but it seems to be overkill 回答1: Firstly, you have typos. ->>

问题 Assuming if I have the following Record typed data, and a hlist of keys: val rr = ("a" ->> 1) :: ("b" -> "s") :: ("c" -> 3) :: HNil val hh = "c" :: "b" :: HNil And I want to extract values in rr for each key in hh , then combine them into a type level object, eventually yielding: (3: Int) :: ("s": String) :: HNil How this can be achieved with least amount of code? I could obviously write a inductively-summoned implicit function but it seems to be overkill 回答1: Firstly, you have typos. ->>

问题 consider i have a json as following: { "a": "aa", "b": "bb", "c": "cc", "d": "dd", // unknown in advance "e": { //unknown in advance "aa": "aa" } } i know for sure that the json will contain a,b,c but i've no idea what other fields this json may contain. i want to serialize this JSON into a case class containing a,b,c but on the other hand not to lose the other fields (save them in a map so the class will be deserialized to the same json as received). ideas? 回答1: One option is to capture the

问题 I have a spark DataFrame. Now I want to do some processing using Weka. Therefore, I want to load data into Weka Instances from the DataFrame and finally return the data as a DataFrame. As the structure both the data type is different, I wondering can anybody help me with the conversion. The code snippet may look like below. val df: DataFrame = data val data: Instances = process(df) 来源： https://stackoverflow.com/questions/58160584/how-to-load-data-in-weka-instances-from-a-spark-dataframe

问题 I have csv format file and is separated by delimiter pipe "|". And the dataset has 2 column, like below . Column1|Column2 1|Name_a 2|Name_b But sometimes we receive only one column value and other is missing like below Column1|Column2 1|Name_a 2|Name_b 3 4 5|Name_c 6 7|Name_f So any row having mismatched column no is a garbage value for us for the above example it will be rows having column value as 3, 4, and 6 and we want to discard these rows. Is there any direct way I can discard those

问题 I have csv format file and is separated by delimiter pipe "|". And the dataset has 2 column, like below . Column1|Column2 1|Name_a 2|Name_b But sometimes we receive only one column value and other is missing like below Column1|Column2 1|Name_a 2|Name_b 3 4 5|Name_c 6 7|Name_f So any row having mismatched column no is a garbage value for us for the above example it will be rows having column value as 3, 4, and 6 and we want to discard these rows. Is there any direct way I can discard those

问题 I am trying to install ScalaZ3 by using the site https://github.com/epfl-lara/ScalaZ3 . I cloned the code into my directory on Windows, opened a Linux terminal and ran sbt +package . At first it returned several errors since I am using Ubuntu Linux subsystem on Windows, so I had to comment out some lines in mk_util.py to make it work. I now encounter another problem where it is trying to run a "make" file but it can't find it. It has the correct directory path and the file exists in that

问题 I am trying to install ScalaZ3 by using the site https://github.com/epfl-lara/ScalaZ3 . I cloned the code into my directory on Windows, opened a Linux terminal and ran sbt +package . At first it returned several errors since I am using Ubuntu Linux subsystem on Windows, so I had to comment out some lines in mk_util.py to make it work. I now encounter another problem where it is trying to run a "make" file but it can't find it. It has the correct directory path and the file exists in that