[Rd] How to create a table structure in Java code?

[Simon Urbanek]

You are entering the quoting hell - you are missing quotes and escapes for \n. it would be much more reasonable to use the rConnection.assign method instead of pasting any content through the parser.

Cheers,
Simon


> On Oct 26, 2017, at 9:59 AM, Morkus via R-devel <r-devel at r-project.org> wrote:
> 
> That's amazing! Thank you!!!
> 
> One follow up question, if that's OK?
> 
> If, instead of using hard-coded CSV, I read the CSV into a variable first, then it fails again with a parse error.
> 
> Code below.
> 
> So, if I read the CSV into a variable, do I need an additional wrapper method?
> 
> Seems like it should still work.
> 
> Thanks in advance for your reply.
> 
> -M
> 
> String inputIris = "5.1,3.5,1.4,0.2,setosa\n" +
> "4.9,3,1.4,0.2,setosa\n" +
> "4.7,3.2,1.3,0.2,setosa\n" +
> "4.6,3.1,1.5,0.2,setosa\n" +
> "5,3.6,1.4,0.2,setosa\n" +
> "5.4,3.9,1.7,0.4,setosa\n" +
> "4.6,3.4,1.4,0.3,setosa";
> 
> REXP irisData =rConnection.eval(
> "read.csv(textConnection(" + inputIris + "), header = FALSE)");
> 
> Sent from [ProtonMail](https://protonmail.com), Swiss-based encrypted email.
> 
>> -------- Original Message --------
>> Subject: Re: [Rd] How to create a table structure in Java code?
>> Local Time: October 26, 2017 7:45 AM
>> UTC Time: October 26, 2017 11:45 AM
>> From: rhelp at eoos.dds.nl
>> To: r-devel at r-project.org
>> 
>> I suspect that you are looking for something like:
>> 
>> read.csv(textConnection(
>> "5.1,3.5,1.4,0.2,setosa
>> 4.9,3,1.4,0.2,setosa
>> 4.7,3.2,1.3,0.2,setosa
>> 4.6,3.1,1.5,0.2,setosa
>> 5,3.6,1.4,0.2,setosa"
>> ), header = FALSE)
>> 
>> HTH,
>> Jan
>> 
>> On 25-10-17 12:50, Morkus via R-devel wrote:
>> 
>>> Hi all,
>>> Using RConsole, it's easy to get data from the database that you can use in an R Command. Like this:
>>> (Reference case)
>>> 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:
>>> 5.1,3.5,1.4,0.2,setosa,
>>> 4.9,3,1.4,0.2,setosa,
>>> 4.7,3.2,1.3,0.2,setosa,
>>> 4.6,3.1,1.5,0.2,setosa,
>>> 5,3.6,1.4,0.2,setosa,
>>> 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" +
>>> "4.9,3,1.4,0.2,setosa\n" +
>>> "4.7,3.2,1.3,0.2,setosa\n" +
>>> "4.6,3.1,1.5,0.2,setosa\n" +
>>> "5,3.6,1.4,0.2,setosa)" ;
>>> // using parseAndEval below to give me actual error R is sending...
>>> REXP rResponseObject = rConnection.parseAndEval("try(eval("+tableRead+"),silent=TRUE)");
>>> if (rResponseObject.inherits("try-error"))
>>> {
>>> 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
>>> at org.rosuda.REngine.Rserve.RConnection.parseAndEval(RConnection.java:454)
>>> at org.rosuda.REngine.REngine.parseAndEval(REngine.java:108)
>>> at net.example.start_r_fromjava.RStatisticsExample.main(RStatisticsExample.java:151)
>>> 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,
>>> 
>>> - M
>>> 
>>> Sent from [ProtonMail](https://protonmail.com), Swiss-based encrypted email.
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>>> ---------------------------------------------------------------
>>> 
>>> R-devel at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>> 
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>> 
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