[Rd] How to create a table structure in Java code?
morkus at protonmail.com
Wed Oct 25 12:50:41 CEST 2017
Using RConsole, it's easy to get data from the database that you can use in an R Command. Like this:
irisQuery <- dbGetQuery(conn, "select * from iris")
boxM(irisQuery [,-5], irisQuery[,5])
(Actual case this posting is about)
Yet, if I'm getting that same (sample IRIS) data, say, in a web service possibly POSTED from a SQL command, that same data might look like this (portion of the included iris data set below). I'm thus not sure how to package the data so R likes it.
Example R-included IRIS data from SQL output:
I've tried various combinations in code to achieve what's simple in RConsole, but I can't get R to accept my structure.
- I've tried just including the data in a string.
- I've tried wrapping the data with "data"
- I've tried wrapping the data with "data.frame" (as below).
Here's my latest attempt:
String tableRead = "data.frame(5.1,3.5,1.4,0.2,setosa\n" +
// using parseAndEval below to give me actual error R is sending...
REXP rResponseObject = rConnection.parseAndEval("try(eval("+tableRead+"),silent=TRUE)");
System.out.println("R Serve Eval Exception : "+rResponseObject.asString());
REXP boxMResult = rConnection.eval("boxM("+ tableRead+ "[,-5]," + tableRead + "[, 5])"); // FAILS <<
Error in the above case is:
Disconnected from the target VM, address: '127.0.0.1:51356', transport: 'socket'
org.rosuda.REngine.REngineException: eval failed, request status: R parser: syntax error
Does the POSTed data need to be in a different format or am I just not framing it correctly?
Would appreciate any tips on how to package table data that might come from a SQL Query passed to Java code.
Thanks very much in advance,
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