R/qgis_mergevectorlayers.R

In JanCaha/r_package_qgis: An extension of package "qgisprocess" providing direct R functions for QGIS functions

##' QGIS Algorithm provided by QGIS (native c++) Merge vector layers (native:mergevectorlayers). Combines multiple vector layers of the same geometry type into a single one. This algorithm combines multiple vector layers of the same geometry type into a single one.  The attribute table of the resulting layer will contain the fields from all input layers. If fields with the same name but different types are found then the exported field will be automatically converted into a string type field. New fields storing the original layer name and source are also added.  If any input layers contain Z or M values, then the output layer will also contain these values. Similarly, if any of the input layers are multi-part, the output layer will also be a multi-part layer.  Optionally, the destination coordinate reference system (CRS) for the merged layer can be set. If it is not set, the CRS will be taken from the first input layer. All layers will all be reprojected to match this CRS.  ---------------- Notes ----------------   - This algorithm drops existing primary keys or FID values and regenerates them in output layers.
##'
##' @title QGIS algorithm - Merge vector layers
##'
##' @param LAYERS `multilayer` - Input layers. .
##' @param CRS `crs` - Destination CRS. CRS as an auth ID (e.g. 'EPSG:3111'). CRS as a PROJ4 string (e.g. 'PROJ4:…'). CRS as a WKT string (e.g. 'WKT:…'). Path to a layer. The CRS of the layer is used..
##' @param OUTPUT `sink` - Merged. Path for new vector layer.
##' @param ... further parameters passed to `qgisprocess::qgis_run_algorithm()`
##' @param .complete_output logical specifying if complete out of `qgisprocess::qgis_run_algorithm()` should be used (`TRUE`) or first output (most likely the main) should read (`FALSE`). Default value is `TRUE`.
##' @param .quiet logical specifying if parameter `.quiet` for `qgisprocess::qgis_run_algorithm()` Default value is `TRUE`.
##' @param .messages logical specifying if messages from `qgisprocess::qgis_run_algorithm()` should be printed (`TRUE`) or not (`FALSE`). Default value is `FALSE`.
##'
##' @details
##' ## Outputs description
##' * OUTPUT - outputVector - Merged
##'
##'
##' @export
##' @md
##' @importFrom qgisprocess qgis_run_algorithm

qgis_mergevectorlayers <- function(LAYERS = qgisprocess:::qgis_default_value(), CRS = qgisprocess:::qgis_default_value(), OUTPUT = qgisprocess:::qgis_default_value(),..., .complete_output = .complete_output_option(), .quiet = .quiet_option(), .messages = .message_option()) {

  check_algorithm_necessities("native:mergevectorlayers")

  if (.messages){
    output <- qgisprocess::qgis_run_algorithm("native:mergevectorlayers", `LAYERS` = LAYERS, `CRS` = CRS, `OUTPUT` = OUTPUT,..., .quiet = .quiet)
  } else {
    suppressMessages(
      output <- qgisprocess::qgis_run_algorithm("native:mergevectorlayers", `LAYERS` = LAYERS, `CRS` = CRS, `OUTPUT` = OUTPUT,..., .quiet = .quiet)
      )
  }

  if (.complete_output) {
    return(output)
  }
  else{
    qgisprocess::qgis_extract_output(output, "OUTPUT")
  }
}