Faster conversion from sf to WKT

The lwgeom package and the use of the global Sys.setenv("LWGEOM_WKT" = "true") option allows faster conversion of simple features objects to well-known text (WKT) representation, due to the use of low-level code. It also enables faster printing of complex geometries. Note that using this method, the output may differ from the default, which can cause reproducibility problems.

Alternatively, you can also use the lwgeom::st_astext() and wk::as_wkt() functions directly.

Code

library("sf")

# generate some data
n = 100000
pts = data.frame(x = rnorm(n), y = rnorm(n))
pts = st_as_sf(pts, coords = c("x", "y"))
pts = st_as_sfc(pts)

system.time(x <- st_as_text(pts))

##    user  system elapsed 
##    7.36    0.16    7.51

x[1]

## [1] "POINT (0.007360117 -1.83104)"

# `lwgeom` must be installed
Sys.setenv("LWGEOM_WKT" = "true")
system.time(y <- st_as_text(pts))

##    user  system elapsed 
##    0.20    0.01    0.22

y[1]

## [1] "POINT(0.0073601 -1.8310401)"