Parsing nodes on JSON with Scala - -

-

i've been asked parse json file buses on specified speed inputed user.

the json file can downloaded here

it's this: 

{ "columns": [     "datahora",     "ordem",     "linha",     "latitude",     "longitude",     "velocidade" ], "data": [     [         "04-16-2015 00:00:55",         "b63099",         "",         -22.7931,         -43.2943,         0     ],     [         "04-16-2015 00:01:02",         "c44503",         781,         -22.853649,         -43.37616,         25     ],     [         "04-16-2015 00:11:40",         "b63067",         "",         -22.7925,         -43.2945,         0     ], ] }

the thing is: i'm new scala , have never worked json before (shame on me). need "ordem", "linha" , "velocidade" data node.

i created case class enclousure data later on specified speed.

case class bus(ordem: string, linha: int, velocidade: int)

i did reading file textfile , spliting. although way, need foreknow content of file in order go lines after data node.

i want know how using json parser. i've tried many solutions, couldn't adapt problem, because need extract lines data node instead of nodes inside 1 node.

can me?

ps: sorry english, not native speaker.

first of all, need understand different json data types. basic types in json numbers, strings, booleans, arrays, , objects. data returned in example object 2 keys: columns , data. columns key has value array of strings , numbers. data key has value array of arrays of strings.

you can use library playjson work type of data:

val js = json.parse(x).as[jsobject] val keys = (js \ "columns").as[list[string]] val values = (js \ "data").as[list[list[jsvalue]]]  val busses = values.map(valuelist => {     val keyvalues = (keys zip valuelist).tomap      {       ordem <- keyvalues("ordem").asopt[string]       linha <- keyvalues("linha").asopt[int]       velocidade <- keyvalues("velocidade").asopt[int]     } yield bus(ordem, linha, velocidade) })

note use of asopt when converting properties expected types. operator converts key-values provided type if possible (wrapped in some), , returns none otherwise. so, if want provide default value instead of ignoring other results, use keyvalues("linha").asopt[int].getorelse(0), example.

you can read more play json methods used here, \ , as, , asopt in their docs.


Comments

Post a Comment

Popular posts from this blog

java - Custom OutputStreamAppender not run: LOGBACK: No context given for <MYAPPENDER> -

-
i wish write custom appender on basis of outputstreamappender . wrote following class package tests; import java.io.ioexception; import java.io.outputstream; import ch.qos.logback.core.outputstreamappender; public class myappender<e> extends outputstreamappender<e> { public myappender() { system.out.println("myappender created"); setoutputstream(new outputstream() { @override public void write(int b) throws ioexception { throw new unsupportedoperationexception(); } }); } } then wrote following runner: package tests; import org.slf4j.loggerfactory; import ch.qos.logback.classic.logger; public class runner { private static final logger log = (logger) loggerfactory.getlogger(runner.class); public static void main(string[] args) { //log.addappender(new myappender<iloggingevent>()); log.info("hello world"); } } finall...
Read more

java - UML - How would you draw a try catch in a sequence diagram? -

-
Image
is there standard way of drawing try catch sequence diagrams? i've made attempt based on this feel end result doesn't feel right. code diagram based around: public static void save () { try { filehandle filehandle = gdx.files.external(file); filehandle.writestring(boolean.tostring(constantshandler.soundenabled)+"\n", false); (int = 0; < 5; i++) { filehandle.writestring(integer.tostring(constantshandler.highscores[i])+"\n", true); } } catch (throwable e) { } } my attempt note: know still need add loop. that's ok. fragments meant show conditional control flow in sequence diagram. superstructures puts limitations on use of fragments (see pp. 467 of ss2.1.1). should use critical region try part above. , option catch . however, keep telling can take quite freedom in using uml. it's language , such changes in life time. long reader ge...
Read more

c++ - No viable overloaded operator for references a map -

-
i trying use map can make tag names reference number. when try , use it, in code error (6 in total every time reference map): src/main.cpp:25:45: error: no viable overloaded operator[] type 'std::map<std::string, std::string>' const char* idcs = node.child_value(tagmap[3]); this code: #include "pugi/pugixml.hpp" #include <iostream> #include <string> #include <map> int main() { pugi::xml_document doca, docb; std::map<std::string, pugi::xml_node> mapa, mapb; std::map<std::string, std::string> tagmap {{"1", "data"}, {"2", "entry"}, {"3", "id"}, {"4", "content"}}; if (!doca.load_file("a.xml") || !docb.load_file("b.xml")) { std::cout << "can't find input files"; return 1; } (auto& node: doca.child(tagmap[1]).children(tagmap[2])) { co...
Read more