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Export sf Minka Objects to a GeoPackage for QGIS

Source: R/export_mnk_qgis.R
export_mnk_qgis.Rd

Writes one or more sf objects to a GeoPackage (.gpkg) with one layer per object. The function is designed for a smooth QGIS workflow: it ensures valid geometries, drops Z/M dimensions, removes list-columns that GDAL cannot write, and transforms to a target CRS.

Usage

export_mnk_qgis(..., file = NULL, crs = 4326, overwrite = TRUE)

Arguments

...

One or more objects of class sf. Each object must be named; the name is used as the layer name in the GeoPackage (e.g., export_mnk_qgis(points = pts, polygons = polys)).

file

Character. Path to the output GeoPackage. It is highly recommended to provide a full path. If a simple filename is provided, it will be saved in the current working directory. The .gpkg extension is added if missing.

crs

CRS to transform to before writing. Accepts anything valid for sf::st_transform() (e.g., 4326 or "EPSG:4326"). Default is 4326 (WGS 84).

overwrite

Logical. If TRUE and file exists, the file is deleted before writing. If FALSE and the file exists, the function appends layers (and will error if a layer name already exists). Default is TRUE.

Value

Invisibly returns the normalized path to the written GeoPackage. Called for its side effect of writing the file.

Details

The function performs the following steps for each layer:

  1. Transform to crs with sf::st_transform().

  2. Drop Z and M dimensions with sf::st_zm().

  3. Repair invalid geometries with sf::st_make_valid().

  4. Remove non-geometry list-columns, which GDAL cannot write to GPKG.

  5. Write the layer with sf::st_write() using the GPKG driver.

If overwrite = TRUE, the existing file is removed first. If the file cannot be removed (e.g., it is open in QGIS), the function stops with an informative error.

Examples

if (FALSE) { # \dontrun{
library(sf)

# points
pts <- st_as_sf(data.frame(id = 1:2, x = c(0.8, 0.9), y = c(40.9, 41.0)),
coords = c("x", "y"), crs = 4326)

# polygon
poly <- st_as_sf(st_sfc(
st_polygon(list(rbind(c(0.7,40.8), c(1.0,40.8), c(1.0,41.1),
c(0.7,41.1), c(0.7,40.8)))),
crs = 4326))
# The names of the layers will be exampl_points and  exampl_area
export_mnk_qgis(exampl_points = pts, exampl_area = poly,
file = tempfile(fileext = ".gpkg"))
} # }