Running examples in 'sf-Ex.R' failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: st_crs
> ### Title: Retrieve coordinate reference system from object
> ### Aliases: st_crs st_crs.sf st_crs.numeric st_crs.character st_crs.sfc
> ###   st_crs.bbox st_crs.CRS st_crs.crs st_crs<- st_crs<-.sf st_crs<-.sfc
> ###   st_set_crs NA_crs_ is.na.crs $.crs
> ### Keywords: datasets
> 
> ### ** Examples
> 
> sfc = st_sfc(st_point(c(0,0)), st_point(c(1,1)))
> sf = st_sf(a = 1:2, geom = sfc)
> st_crs(sf) = 4326
> st_geometry(sf)
Geometry set for 2 features 
geometry type:  POINT
dimension:      XY
bbox:           xmin: 0 ymin: 0 xmax: 1 ymax: 1
epsg (SRID):    4326
proj4string:    +proj=longlat +datum=WGS84 +no_defs
POINT (0 0)
POINT (1 1)
> sfc = st_sfc(st_point(c(0,0)), st_point(c(1,1)))
> st_crs(sfc) = 4326
> sfc
Geometry set for 2 features 
geometry type:  POINT
dimension:      XY
bbox:           xmin: 0 ymin: 0 xmax: 1 ymax: 1
epsg (SRID):    4326
proj4string:    +proj=longlat +datum=WGS84 +no_defs
POINT (0 0)
POINT (1 1)
> sfc = st_sfc(st_point(c(0,0)), st_point(c(1,1)))
> library(dplyr)

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

> x = sfc %>% st_set_crs(4326) %>% st_transform(3857)
> x
Geometry set for 2 features 
geometry type:  POINT
dimension:      XY
bbox:           xmin: 0 ymin: 0 xmax: 111319.5 ymax: 111325.1
epsg (SRID):    3857
proj4string:    +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs
POINT (0 0)
POINT (111319.5 111325.1)
> st_crs("+init=epsg:3857")$epsg
proj_create: init=epsg:/init=IGNF: syntax not supported in non-PROJ4 emulation mode
[1] 3857
> st_crs("+init=epsg:3857")$proj4string
proj_create: init=epsg:/init=IGNF: syntax not supported in non-PROJ4 emulation mode
[1] "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"
> st_crs("+init=epsg:3857 +units=m")$b     # numeric
proj_create: init=epsg:/init=IGNF: syntax not supported in non-PROJ4 emulation mode
Warning in CPL_crs_from_proj4string(x) :
  GDAL cannot import PROJ.4 string `+init=epsg:3857 +units=m': returning missing CRS
Error in if (!is.null(u) && crs$units != u) stop(paste0("units ", u, " not recognized: older GDAL version?"),  : 
  missing value where TRUE/FALSE needed
Calls: st_crs -> st_crs.character -> make_crs
Execution halted