R language scalar function 2

The following function calculates the total length of the character input columns.

Code

Enter the following code in the /tmp/rlength.R file:

nz.fun <- function () {
while(getNext()) {
s <- 0
for (i in seq(inputColumnCount())) {
x <- getInputColumn(i-1)
if (is.character(x)) {
s <- s + nchar(x)
}
}
if (s == 0) {
stop('no character columns in input')
}
setOutputInt32(0, s)
outputResult()
}
}

Compilation

Compile the code as follows:

/nz/export/ae/utilities/bin/compile_ae --language r \
--version 3 --template compile --user nz --db dev \
/tmp/rlength.R

Registration

To take full advantage of the R code, register the compiled UDAP with the VARARGS input signature. This signature indicates that the specific function can handle any number of arguments of arbitrary types:

/nz/export/ae/utilities/bin/register_ae --language r \
--version 3 --user nz --db dev --template udf \
--sig 'rlength(VARARGS)' --return INT4 --exe rlength.R

In these examples the user is specified as nz, which is an example user ID. The value that you use should be a valid database user name.

Running

When you run this function, you get the following result:

SELECT rlength('sample text');
RLENGTH
---------
11
(1 row)

When you run this function for a table iris, which is a copy of the standard R iris data set you get the following result:

SELECT rlength(SPECIES) FROM iris;
RLENGTH
---------
6
6
6
(147 more rows)

The following example shows the use of the VARARGS input signature:

SELECT rlength('sample text',1, 'another text',2,3,4,'and one more text');
RLENGTH
---------
40
(1 row)