The package contains functions to calculate some point estimators and estimating their sampling variance under unequal-probability sampling. Uni-stage and two-stage sampling designs are considered. Some approximations for the joint-inclusion probabilities (sample and population based) are available... More details here.
Interfacing C in R
You might find high-time-consuming some codes with loads of loops and that are entirely written in R. A solution is to write codes in C and interface them in R. Loops that take "ages" are reduced to seconds. These are some easy-to-follow steps; collected from several sources (PhD studies, manuals and on-line references).