.. only:: html Vector selection ================ .. only:: html .. contents:: :local: :depth: 1 .. _qgisextractbyattribute: Extract by attribute -------------------- Creates two vector layers from an input layer: one will contain only matching features while the second will contain all the non-matching features. The criteria for adding features to the resulting layer is defined based on the values of an attribute from the input layer. Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Layer to extract features from. * - **Selection attribute** - ``FIELD`` - [tablefield: any] - Filtering field of the layer * - **Operator** - ``OPERATOR`` - [enumeration] Default: 0 - Many different operators are available: * 0 --- = * 1 --- ≠ * 2 --- > * 3 --- >= * 4 --- < * 5 --- <= * 6 --- begins with * 7 --- contains * 8 --- is null * 9 --- is not null * 10 --- does not contain * - **Value** Optional - ``VALUE`` - [string] - Value to be evaluated * - **Extracted (attribute)** - ``OUTPUT`` - [same as input] Default: ``[Create Temporary Layer]`` - Specify the output vector layer for matching features. One of: * Create Temporary Layer (``TEMPORARY_OUTPUT``) * Save to File... * Save to Geopackage... * Save to PostGIS Table The file encoding can also be changed here. * - **Extracted (non-matching)** - ``FAIL_OUTPUT`` - [same as input] Default: ``[Skip output]`` - Specify the output vector layer for non-matching features. One of: * Skip Output * Create Temporary Layer (``TEMPORARY_OUTPUT``) * Save to File... * Save to Geopackage... * Save to PostGIS Table Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Extracted (attribute)** - ``OUTPUT`` - [same as input] - Vector layer with matching features from the input layer * - **Extracted (non-matching)** - ``FAIL_OUTPUT`` - [same as input] - Vector layer with non-matching features from the input layer See also ........ :ref:`qgisselectbyattribute` .. _qgisextractbyexpression: Extract by expression --------------------- Creates two vector layers from an input layer: one will contain only matching features while the second will contain all the non-matching features. The criteria for adding features to the resulting layer is based on a QGIS expression. For more information about expressions see the :ref:`vector_expressions`. Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Input vector layer * - **Expression** - ``EXPRESSION`` - [expression] - Expression to filter the vector layer * - **Matching features** - ``OUTPUT`` - [same as input] Default: ``[Create Temporary Layer]`` - Specify the output vector layer for matching features. One of: * Create Temporary Layer (``TEMPORARY_OUTPUT``) * Save to File... * Save to Geopackage... * Save to PostGIS Table The file encoding can also be changed here. * - **Non-matching** - ``FAIL_OUTPUT`` - [same as input] Default: ``[Skip output]`` - Specify the output vector layer for non-matching features. One of: * Skip Output * Create Temporary Layer (``TEMPORARY_OUTPUT``) * Save to File... * Save to Geopackage... * Save to PostGIS Table Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Matching features** - ``OUTPUT`` - [same as input] - Vector layer with matching features from the input layer * - **Non-matching** - ``FAIL_OUTPUT`` - [same as input] - Vector layer with non-matching features from the input layer See also ........ :ref:`qgisselectbyexpression` .. _qgisextractbylocation: Extract by location ------------------- Creates a new vector layer that only contains matching features from an input layer. The criteria for adding features to the resulting layer is defined based on the spatial relationship between each feature and the features in an additional layer. Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Extract features from** - ``INPUT`` - [vector: any] - Input vector layer * - **Where the features (geometric predicate)** - ``PREDICATE`` - [enumeration] [list] Default: [0] - Spatial condition for the selection. One or more of: * 0 --- intersect * 1 --- contain * 2 --- disjoint * 3 --- equal * 4 --- touch * 5 --- overlap * 6 --- are within * 7 --- cross If more than one condition is chosen, at least one of them (OR operation) has to be met for a feature to be extracted. * - **By comparing to the features from** - ``INTERSECT`` - [vector: any] - Intersection vector layer * - **Extracted (location)** - ``OUTPUT`` - [same as input] Default: ``[Create temporary layer]`` - Specify the output vector layer for the features that have the chosen spatial relationship(s) with one or more features in the comparison layer. One of: * Create Temporary Layer (``TEMPORARY_OUTPUT``) * Save to File... * Save to Geopackage... * Save to PostGIS Table Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Extracted (location)** - ``OUTPUT`` - [same as input] - Vector layer with features from the input layer that have the chosen spatial relationship(s) with one or more features in the comparison layer. See also ........ :ref:`qgisselectbylocation` .. _qgisrandomextract: Random extract -------------- Takes a vector layer and generates a new one that contains only a subset of the features in the input layer. The subset is defined randomly, based on feature IDs, using a percentage or count value to define the total number of features in the subset. Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Source vector layer to select the features from * - **Method** - ``METHOD`` - [enumeration] Default: 0 - Random selection method. One of: * 0 --- Number of selected features * 1 --- Percentage of selected features * - **Number/percentage of selected features** - ``NUMBER`` - [number] Default: 10 - Number or percentage of features to select * - **Extracted (random)** - ``OUTPUT`` - [vector: any] Default: ``[Create temporary layer]`` - Specify the output vector layer for the randomly selected features. One of: * Create Temporary Layer (``TEMPORARY_OUTPUT``) * Save to File... * Save to Geopackage... * Save to PostGIS Table Vector layer containing randomly selected features Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Extracted (random)** - ``OUTPUT`` - [same as input] - Vector layer containing randomly selected features from the input layer See also ........ :ref:`qgisrandomselection` .. _qgisrandomextractwithinsubsets: Random extract within subsets ----------------------------- Takes a vector layer and generates a new one that contains only a subset of the features in the input layer. The subset is defined randomly, based on feature IDs, using a percentage or count value to define the total number of features in the subset. The percentage/count value is not applied to the whole layer, but instead to each category. Categories are defined according to a given attribute. Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Vector layer to select the features from * - **ID field** - ``FIELD`` - [tablefield: any] - Category of the source vector layer to select the features from * - **Method** - ``METHOD`` - [enumeration] Default: 0 - Random selection method. One of: * 0 --- Number of selected features * 1 --- Percentage of selected features * - **Number/percentage of selected features** - ``NUMBER`` - [number] Default: 10 - Number or percentage of features to select * - **Extracted (random stratified)** - ``OUTPUT`` - [same as input] Default: ``[Create temporary layer]`` - Specify the output vector layer for the randomly selected features. One of: * Create Temporary Layer (``TEMPORARY_OUTPUT``) * Save to File... * Save to Geopackage... * Save to PostGIS Table The file encoding can also be changed here. Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Extracted (random stratified)** - ``OUTPUT`` - [same as input] - Vector layer containing randomly selected features from the input layer See also ........ :ref:`qgisrandomselectionwithinsubsets` .. _qgisrandomselection: Random selection ---------------- Takes a vector layer and selects a subset of its features. No new layer is generated by this algorithm. The subset is defined randomly, based on feature IDs, using a percentage or count value to define the total number of features in the subset. ``Default menu``: :menuselection:`Vector --> Research Tools` Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Vector layer for the selection * - **Method** - ``METHOD`` - [enumeration] Default: 0 - Random selection method. One of: * 0 --- Number of selected features * 1 --- Percentage of selected features * - **Number/percentage of selected features** - ``NUMBER`` - [number] Default: 10 - Number or percentage of features to select Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [same as input] - The input layer with features selected See also ........ :ref:`qgisrandomextract` .. _qgisrandomselectionwithinsubsets: Random selection within subsets ------------------------------- Takes a vector layer and selects a subset of its features. No new layer is generated by this algorithm. The subset is defined randomly, based on feature IDs, using a percentage or count value to define the total number of features in the subset. The percentage/count value is not applied to the whole layer, but instead to each category. Categories are defined according to a given attribute, which is also specified as an input parameter for the algorithm. No new outputs are created. ``Default menu``: :menuselection:`Vector --> Research Tools` Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Vector layer to select features in * - **ID field** - ``FIELD`` - [tablefield: any] - Category of the input layer to select the features from * - **Method** - ``METHOD`` - [enumeration] Default: 0 - Random selection method. One of: * 0 --- Number of selected features * 1 --- Percentage of selected features * - **Number/percentage of selected features** - ``NUMBER`` - [number] Default: 10 - Number or percentage of features to select Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [same as input] - The input layer with features selected See also ........ :ref:`qgisrandomextractwithinsubsets` .. _qgisselectbyattribute: Select by attribute ------------------- Creates a selection in a vector layer. The criteria for selected features is defined based on the values of an attribute from the input layer. No new outputs are created. Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Vector layer to select features in * - **Selection attribute** - ``FIELD`` - [tablefield: any] - Filtering field of the layer * - **Operator** - ``OPERATOR`` - [enumeration] Default: 0 - Many different operators are available: * 0 --- = * 1 --- ≠ * 2 --- > * 3 --- >= * 4 --- < * 5 --- <= * 6 --- begins with * 7 --- contains * 8 --- is null * 9 --- is not null * 10 --- does not contain * - **Value** Optional - ``VALUE`` - [string] - Value to be evaluated * - **Modify current selection by** - ``METHOD`` - [enumeration] Default: 0 - How the selection of the algorithm should be managed. One of: * 0 --- creating new selection * 1 --- adding to current selection * 2 --- selecting within current selection * 3 --- removing from current selection Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [same as input] - The input layer with features selected See also ........ :ref:`qgisextractbyattribute` .. _qgisselectbyexpression: Select by expression -------------------- Creates a selection in a vector layer. The criteria for selecting features is based on a QGIS expression. For more information about expressions see the :ref:`vector_expressions`. No new outputs are created. Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [vector: any] - Input vector layer * - **Expression** - ``EXPRESSION`` - [expression] - Expression to filter the input layer * - **Modify current selection by** - ``METHOD`` - [enumeration] Default: 0 - How the selection of the algorithm should be managed. One of: * 0 --- creating new selection * 1 --- adding to current selection * 2 --- selecting within current selection * 3 --- removing from current selection Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [same as input] - The input layer with features selected See also ........ :ref:`qgisextractbyexpression` .. _qgisselectbylocation: Select by location ------------------ Creates a selection in a vector layer. The criteria for selecting features is based on the spatial relationship between each feature and the features in an additional layer. No new outputs are created. ``Default menu``: :menuselection:`Vector --> Research Tools` Parameters .......... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Select features from** - ``INPUT`` - [vector: any] - Input vector layer * - **Where the features (geometric predicate)** - ``PREDICATE`` - [enumeration] [list] Default: [0] - Spatial condition for the selection. One or more of: * 0 --- intersect * 1 --- contain * 2 --- disjoint * 3 --- equal * 4 --- touch * 5 --- overlap * 6 --- are within * 7 --- cross If more than one condition is chosen, at least one of them (OR operation) has to be met for a feature to be extracted. * - **By comparing to the features from** - ``INTERSECT`` - [vector: any] - Intersection vector layer * - **Modify current selection by** - ``METHOD`` - [enumeration] Default: 0 - How the selection of the algorithm should be managed. One of: * 0 --- creating new selection * 1 --- adding to current selection * 2 --- selecting within current selection * 3 --- removing from current selection Outputs ....... .. list-table:: :header-rows: 1 :widths: 20 20 20 40 :stub-columns: 0 * - Label - Name - Type - Description * - **Input layer** - ``INPUT`` - [same as input] - The input layer with features selected See also ........ :ref:`qgisextractbylocation`