Figure 1: A screenshot of the corrected and enhanced dynamic visualization of RDS. Green balls are convenience sample, pink balls are subsequently recruited individuals, pink lines are links between network nodes that have been explored by the process, and numbers in circles correspond to sample wave number.
It is common to hear that R is slow, and so when I faced the necessity to scale old R code (pertaining to material described in this post) to operate on data 100 times larger than it used to, I was initially at a loss. The problem with the old code was that it took several days and about 4000 semi-parallel jobs to complete. With the size of data increasing by a factor of 100, the task was becoming infeasible to complete. Eventually however, I was able to achieve an over 100-fold speedup of the R code, with the speedup being due to addressing two issues: (more…)