[R] an SJava array question

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From: Rajarshi Guha (rxg218@psu.edu)
Date: Thu 27 May 2004 - 06:44:35 EST


Message-id: <1085604274.9434.9.camel@blue.chem.psu.edu>

Hi,
  I'm using SJava (0.65) to interface some Java code I have and am
having trouble understanding the use of arrays. I have a function:

tmv <- function(fname) {
    a <- .JavaArrayConstructor("int", dim=c(3,0))
    .JavaSetArrayElement(a, .JavaArrayConstructor("int", dim=3), 1)
    .JavaSetArrayElement(a, .JavaArrayConstructor("int", dim=3), 2)
    .JavaSetArrayElement(a, .JavaArrayConstructor("int", dim=3), 3)
    for (i in 1:3) {
        for (j in 1:3) {
            .JavaSetArrayElement(a, as.integer(i*j), i,j)
        }
    }
    print(.JavaGetArrayElement(a, 1,1))
}

I expect that I should see 1 print out but instead I get

[[1]]
[1] 1 2 3
 
[[2]]
[1] 1 2 3

The SJava manual seems to indicate that .JavaGetArrayElement(a, 1,1)
gives the first element of the first array.

Could anybody throw some light on this?

A related question is the an array of Strings.

Does .JavaArrayConstructor("String",3) give me an array of 3 Strings
(which are not yet defined) or a String of length 3? Or if I need to
allocate an array of Strings should I do:

r <- .JavaArrayConstructor( "String", c(3,0) )

and then for each element of r add a new array and then finally set the
individual elements to the actuial string values?

Is there any example code available that I could take a look at?

Thanks,

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Rajarshi Guha <rxg218@psu.edu> <http://jijo.cjb.net>
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