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Morkus

2017-Oct-25 10:50 UTC

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

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.
	[[alternative HTML version deleted]]

Jan van der Laan

2017-Oct-26 11:45 UTC

head link

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

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.
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

Morkus

2017-Oct-26 13:59 UTC

head link

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

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.
>> [[alternative HTML version deleted]]
>> ---------------------------------------------------------------
>>
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>
> ---------------------------------------------------------------
>
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel	[[alternative HTML version deleted]]

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