[Rcpp-devel] Yet another instance of "function 'dataptr' not provided ..."

[Douglas Bates]

I must have been away from writing R/Rcpp code for too long.

I started off trying to reproduce a calculation that is, literally, a
one-liner in Julia.  See

http://nbviewer.ipython.org/gist/dmbates/9746197

Now admittedly the calculation of the sums of the n choose k possible
subsets of size k from a vector or length n is aided by the fact that there
is a combinations iterator in Julia.  Nonetheless it is pretty amazing that
this can be written as

combsums(v::Vector, k) = [sum(c) for c in combinations(v,k)]

using this iterator and a comprehension.

I tried to write the combinations iterator in C++ but eventually tied
myself in knots so I decided to back off and write a function that does the
equivalent of the R function sample() and use that to generate a random
sample from the distribution of sums.

I have the C++ code working using Rcpp attributes but now I must generate a
package.  I have to be missing something obvious because my attempt at

http://github.com/dmbates/randomizationTest

produces the dread "function 'dataptr' not provided ..." message when I try
to invoke the R function randomsums.

Which of the many vignettes or manuals should I start reading?

(I can't believe I have spent two days going through innumerable
contortions to try to achieve the effect of a one-liner.)
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