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Created by Dave Berry@dybMaintainer

use of R bind in new_merge_ids_year

Iterative use of rbind (i.e. in a loop) leads to poor performance, recommend preallocating data frames and then filling.

Preallocate data frame

Line 399:

tr.add <- c()

replace with

   max_rows = nrow( mdata )
   tr.add <- data.frame( uid <- rep(NA_character_, max_rows), trk = rep(NA_integer_, max_rows), few = rep(NA_integer_, max_rows), 
        speed = rep(NA_real_, max_rows), course = rep(NA_real_, max_rows) )
   row_position <- 0

Fill

Line 461:

tr.add<-rbind(tr.add,data.frame(tr))

replace with

      tr.add[ row_position + 1:length(tr$uid) , ] <- data.frame( tr )
      row_position <- row_position + length(tr$uid)

and then at end of loop between lines 464 and 465 insert

tr.add <- tr.add[ 1:row_position, ]

I've only tested very briefly so the above needs checking fully.

Edited by Dave Berry