Convert sequence of longitude and latitude to polygon via sf in R

Question

I have five longitude and latitude that form a shape like this.

df <- c(order=1:5,
        lon=c(119.4,119.4,119.4,119.5,119.5), 
        lat=c(-5.192,-5.         


        

Answer 1

library(sfheaders) on CRAN from 20191004 can take a data.frame and convert it to sf objects

library(sf)
library(sfheaders)

df <- data.frame(
  lon = c(119.4, 119.4, 119.4, 119.5, 119.5),
  lat = c(-5.192, -5.192, -5.187, -5.187, -5.191)
)

sfheaders::sf_polygon(
  obj = df
)
## given only two columns of data are in df there's no need to specify lon & lat arguments

# Simple feature collection with 1 feature and 1 field
# geometry type:  POLYGON
# dimension:      XY
# bbox:           xmin: 119.4 ymin: -5.192 xmax: 119.5 ymax: -5.187
# epsg (SRID):    NA
# proj4string:    
#   id                       geometry
# 1  1 POLYGON ((119.4 -5.192, 119...