R – How to Load a CSV as Simple Features

rsf

Is there a direct way to load a CSV as an sf? I've looked through the sf documentation and nothing jumps out at me, currently using:

my_csv <- read.csv('my_data.csv', header = TRUE)

my_sp <- sp::SpatialPointsDataFrame(coords = data.frame(my_csv$y, 
my_csv$x), data = data.frame(my_csv$data), proj4string = CRS(BNG))

my_sf <- sf::st_as_sf(my_sp)

Best Answer

When you read a CSV with no options the driver doesn't know where the coordinate columns are so returns a data frame:

library(sf)
> st_read("./pts.csv")
Reading layer `pts' from data source `/home/rowlings/Downloads/SO/csv/pts.csv' using driver `CSV'
  id     x     y
1  1  10.1   2.1
2  2   2.4  12.1
3  3   3.2   4.5
Warning message:
no simple feature geometries present: returning a data.frame or tbl_df

So you need to pass a couple of options that end up telling the OGR driver where the coordinates are:

library(sf)
> st_read("./pts.csv", options=c("X_POSSIBLE_NAMES=x","Y_POSSIBLE_NAMES=y"))
options:        X_POSSIBLE_NAMES=x Y_POSSIBLE_NAMES=y 
Reading layer `pts' from data source `/home/rowlings/Downloads/SO/csv/pts.csv' using driver `CSV'
Simple feature collection with 3 features and 3 fields
geometry type:  POINT
dimension:      XY
bbox:           xmin: 2.4 ymin: 2.1 xmax: 10.1 ymax: 12.1
epsg (SRID):    NA
proj4string:    NA

and there's your sf spatial object.

OGR CSV driver documentation is here: https://gdal.org/drv_csv.html

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