QGIS algorithm - Join attributes by field value

Source: R/qgis_joinattributestable.R

QGIS Algorithm provided by QGIS (native c++) Join attributes by field value (native:joinattributestable). This algorithm takes an input vector layer and creates a new vector layer that is an extended version of the input one, with additional attributes in its attribute table. The additional attributes and their values are taken from a second vector layer. An attribute is selected in each of them to define the join criteria. —————- Notes —————- - This algorithm drops existing primary keys or FID values and regenerates them in output layers.

qgis_joinattributestable(
  INPUT = qgisprocess:::qgis_default_value(),
  FIELD = qgisprocess:::qgis_default_value(),
  INPUT_2 = qgisprocess:::qgis_default_value(),
  FIELD_2 = qgisprocess:::qgis_default_value(),
  FIELDS_TO_COPY = qgisprocess:::qgis_default_value(),
  METHOD = qgisprocess:::qgis_default_value(),
  DISCARD_NONMATCHING = qgisprocess:::qgis_default_value(),
  PREFIX = qgisprocess:::qgis_default_value(),
  OUTPUT = qgisprocess:::qgis_default_value(),
  NON_MATCHING = 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.

FIELD

field - Table field. The name of an existing field. ; delimited list of existing field names.

INPUT_2

source - Input layer 2. Path to a vector layer.

FIELD_2

field - Table field 2. The name of an existing field. ; delimited list of existing field names.

FIELDS_TO_COPY

field - Layer 2 fields to copy (leave empty to copy all fields). The name of an existing field. ; delimited list of existing field names.

METHOD

enum of ("Create separate feature for each matching feature (one-to-many)", "Take attributes of the first matching feature only (one-to-one)") - Join type. Number of selected option, e.g. '1'. Comma separated list of options, e.g. '1,3'.

DISCARD_NONMATCHING

boolean - Discard records which could not be joined. 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.

PREFIX

string - Joined field prefix. String value. 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.

OUTPUT

sink - Joined layer. Path for new vector layer.

NON_MATCHING

sink - Unjoinable features from first layer. 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

  • JOINED_COUNT - outputNumber - Number of joined features from input table

  • NON_MATCHING - outputVector - Unjoinable features from first layer

  • OUTPUT - outputVector - Joined layer

  • UNJOINABLE_COUNT - outputNumber - Number of unjoinable features from input table