QGIS algorithm - Geometry by expression

Source: R/qgis_geometrybyexpression.R

QGIS Algorithm provided by QGIS (native c++) Geometry by expression (native:geometrybyexpression). This algorithm updates existing geometries (or creates new geometries) for input features by use of a QGIS expression. This allows complex geometry modifications which can utilize all the flexibility of the QGIS expression engine to manipulate and create geometries for output features. For help with QGIS expression functions, see the inbuilt help for specific functions which is available in the expression builder.

qgis_geometrybyexpression(
  INPUT = qgisprocess:::qgis_default_value(),
  OUTPUT_GEOMETRY = qgisprocess:::qgis_default_value(),
  WITH_Z = qgisprocess:::qgis_default_value(),
  WITH_M = qgisprocess:::qgis_default_value(),
  EXPRESSION = qgisprocess:::qgis_default_value(),
  OUTPUT = qgisprocess:::qgis_default_value(),
  ...,
  .complete_output = .complete_output_option(),
  .quiet = .quiet_option(),
  .messages = .message_option()
)

Arguments

INPUT

source - Input layer. Path to a vector layer.

OUTPUT_GEOMETRY

enum of ("Polygon", "Line", "Point") - Output geometry type. Number of selected option, e.g. '1'. Comma separated list of options, e.g. '1,3'.

WITH_Z

boolean - Output geometry has z dimension. 1 for true/yes. 0 for false/no. field:FIELD_NAME to use a data defined value taken from the FIELD_NAME field. expression:SOME EXPRESSION to use a data defined value calculated using a custom QGIS expression.

WITH_M

boolean - Output geometry has m values. 1 for true/yes. 0 for false/no. field:FIELD_NAME to use a data defined value taken from the FIELD_NAME field. expression:SOME EXPRESSION to use a data defined value calculated using a custom QGIS expression.

EXPRESSION

expression - Geometry expression. A valid QGIS expression string, e.g "road_name" = 'MAIN RD'.

OUTPUT

sink - Modified geometry. Path for new vector layer.

...

further parameters passed to qgisprocess::qgis_run_algorithm()

.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.

.quiet

logical specifying if parameter .quiet for qgisprocess::qgis_run_algorithm() Default value is TRUE.

.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 - Modified geometry