Fast combining objects

Combining vector data using rbind() or dplyr::bind_rows() can be very slow in {sf}. A faster alternative is to use data.table::rbindlist() or collapse::unlist2d(). Note, make sure all objects have the same CRS beforehand!!

Code

library("sf")
library("data.table")

nc = read_sf(system.file("shape/nc.shp", package = "sf"))
ls = vector("list", 500)
for (i in seq_along(ls)) ls[[i]] = nc

system.time({
  dt = rbindlist(ls, use.names = FALSE)
  dt[["geometry"]] = st_sfc(dt[["geometry"]], recompute_bbox = TRUE)
  dt = st_as_sf(dt)
})

##    user  system elapsed 
##    0.05    0.00    0.04

dim(dt)

## [1] 50000    15

system.time({
  df_sf = do.call(rbind, ls)
})

##    user  system elapsed 
##    8.87    0.16    9.03

dim(df_sf)

## [1] 50000    15