... and related to Ravi's post, will there always be at least one date in file 2 that matches every date in file 1? And if there isn't, what action should be taken?
-- Bert On Thu, Jul 23, 2026 at 9:36 AM Ravi Varadhan via R-help < [email protected]> wrote: > This is a classic matching problem, I believe. Based on your description, > you are looking for a 1-to-1 nearest-neighbor match based on the absolute > difference in dates, with the constraint that once a subject in File 2 is > used, all of their records are discarded. > > Correct? > > There are two classical approaches: greedy matching and global optimal > matching. While the greedy approach is simple to implement and often > works, it can sometimes get into trouble (i.e., run out of good matches). > The optimal approach would use the Hungarian algorithm (e.g., LSAP function > in the clue package) to find the combination of matches that results in the > lowest total date difference across the entire dataset. > > Ravi > > [[alternative HTML version deleted]] > > ______________________________________________ > [email protected] mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > https://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ [email protected] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
