CODEWITHSUNDEEP
rdll
kosa
kosa

Reputation: 66637

How to call core C function in R code?

I am trying to call C function provided by R (default installation) for HoltWinters in my own R script, but getting message:

Error in hw(alpha, beta, gamma) : object 'C_HoltWinters' not found

And part of the code in my R script is:

 hw <- function(alpha, beta, gamma)
        .C(C_HoltWinters,
           as.double(x),
           lenx,
           as.double(max(min(alpha, 1), 0)),
           as.double(max(min(beta, 1), 0)),
           as.double(max(min(gamma, 1), 0)),
           as.integer(start.time),
           ## no idea why this is so: same as seasonal != "multiplicative"
           as.integer(! + (seasonal == "multiplicative")),
           as.integer(f),
           as.integer(!is.logical(beta) || beta),
           as.integer(!is.logical(gamma) || gamma),

           a = as.double(l.start),
           b = as.double(b.start),
           s = as.double(s.start),

       ## return values
           SSE = as.double(0),
           level = double(len + 1L),
           trend = double(len + 1L),
           seasonal = double(len + f)
           )

Based on my preliminary research, it seems we need to use dyn.load(dllName);

I have 2 questions now:

1) How can I find out `dll` name for this function? 
2) If I run default `HoltWinters.R` we don't need to load `dll`, then why it is required load `dll` in my custom script case?

Upvotes: 0

Views: 249

Answers (1)

Joshua Ulrich
Joshua Ulrich

Reputation: 176638

The C_HoltWinters object is not exported from the stats namespace. You can reference it using stats:::C_HoltWinters.

Do note that this is against CRAN policy, so it won't be allowed if you put this into a package you plan to submit to CRAN.

Upvotes: 1

Related Questions