Vector geoprocessing
====================
.. only:: html
.. contents::
:local:
:depth: 1
.. _gdalbuffervectors:
Buffer vectors
--------------
Create buffers around the features of a vector layer.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Input layer**
- ``INPUT``
- [vector: any]
- The input vector layer
* - **Geometry column name**
- ``GEOMETRY``
- [string]
Default: 'geometry'
- The name of the input layer geometry column to use
* - **Buffer distance**
- ``DISTANCE``
- [number]
Default: 10.0
- Minimum: 0.0
* - **Dissolve by attribute**
Optional
- ``FIELD``
- [tablefield: any]
Default: None
- Field to use for dissolving
* - **Dissolve results**
- ``DISSOLVE``
- [boolean]
Default: False
- If set, the result is dissolved.
If no field is set for dissolving, all the buffers are
dissolved into one feature.
* - **Produce one feature for each geometry in any kind of
geometry collection in the source file**
- ``EXPLODE_COLLECTIONS``
- [boolean]
Default: False
-
* - **Buffer**
- ``OUTPUT``
- [vector: polygon]
Default: ``[Save to temporary file]``
- Specify the output buffer layer. One of:
.. include:: ../algs_include.rst
:start-after: **file_output_types**
:end-before: **end_file_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Additional creation options**
Optional
- ``OPTIONS``
- [string]
Default: '' (no additional options)
- Additional GDAL creation options.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Buffer**
- ``OUTPUT``
- [vector: polygon]
- The output buffer layer
Python code
...........
**Algorithm ID**: ``gdal:buffervectors``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _gdalclipvectorbyextent:
Clip vector by extent
----------------------
Clips any OGR-supported vector file to a given extent.
This algorithm is derived from the
`GDAL ogr2ogr utility <https://gdal.org/en/latest/programs/ogr2ogr.html>`_.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Input layer**
- ``INPUT``
- [vector: any]
- The input vector layer
* - **Clip extent**
- ``EXTENT``
- [extent]
- Defines the bounding box that should be used for the
output vector file.
It has to be defined in target CRS coordinates.
.. include:: ../algs_include.rst
:start-after: **extent_options**
:end-before: **end_extent_options**
* - **Clipped (extent)**
- ``OUTPUT``
- [same as input]
Default: ``[Save to temporary file]``
- Specify the output (clipped) layer. One of:
.. include:: ../algs_include.rst
:start-after: **file_output_types**
:end-before: **end_file_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Additional creation options**
Optional
- ``OPTIONS``
- [string]
Default: '' (no additional options)
- Additional GDAL creation options.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Clipped (extent)**
- ``OUTPUT``
- [same as input]
- The output (clipped) layer.
The default format is "ESRI Shapefile".
Python code
...........
**Algorithm ID**: ``gdal:clipvectorbyextent``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _gdalclipvectorbypolygon:
Clip vector by mask layer
-------------------------
Clips any OGR-supported vector layer by a mask polygon layer.
This algorithm is derived from the `GDAL ogr2ogr utility
<https://gdal.org/en/latest/programs/ogr2ogr.html>`_.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Input layer**
- ``INPUT``
- [vector: any]
- The input vector layer
* - **Mask layer**
- ``MASK``
- [vector: polygon]
- Layer to be used as clipping extent for the input vector layer.
* - **Clipped (mask)**
- ``OUTPUT``
- [same as input]
Default: ``[Save to temporary file]``
- The output (masked) layer. One of:
.. include:: ../algs_include.rst
:start-after: **file_output_types**
:end-before: **end_file_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Additional creation options**
Optional
- ``OPTIONS``
- [string]
Default: '' (no additional options)
- Additional GDAL creation options.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Clipped (mask)**
- ``OUTPUT``
- [same as input]
- The output (masked) layer.
The default format is "ESRI Shapefile".
Python code
...........
**Algorithm ID**: ``gdal:clipvectorbypolygon``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _gdaldissolve:
Dissolve
--------
Dissolve (combine) geometries that have the same value for
a given attribute / field.
The output geometries are multipart.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Input layer**
- ``INPUT``
- [vector: any]
- The input layer to dissolve
* - **Dissolve field**
Optional
- ``FIELD``
- [tablefield: any]
- The field of the input layer to use for dissolving
* - **Geometry column name**
- ``GEOMETRY``
- [string]
Default: 'geometry'
- The name of the input layer geometry column to use
for dissolving.
* - **Dissolved**
- ``OUTPUT``
- [same as input]
Default: ``[Save to temporary file]``
- Specify the output layer. One of:
.. include:: ../algs_include.rst
:start-after: **file_output_types**
:end-before: **end_file_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Produce one feature for each geometry in any kind of
geometry collection in the source file**
- ``EXPLODE_COLLECTIONS``
- [boolean]
Default: False
- Produce one feature for each geometry in any kind of geometry
collection in the source file
* - **Keep input attributes**
- ``KEEP_ATTRIBUTES``
- [boolean]
Default: False
- Keep all attributes from the input layer
* - **Count dissolved features**
- ``COUNT_FEATURES``
- [boolean]
Default: False
- Count the dissolved features and include it in the output
layer.
* - **Compute area and perimeter of dissolved features**
- ``COMPUTE_AREA``
- [boolean]
Default: False
- Compute the area and perimeter of dissolved features and
include them in the output layer
* - **Compute min/max/sum/mean for attribute**
- ``COMPUTE_STATISTICS``
- [boolean]
Default: False
- Calculate statistics (min, max, sum and mean) for the numeric
attribute specified and include them in the output layer
* - **Numeric attribute to calculate statistics on**
Optional
- ``STATISTICS_ATTRIBUTE``
- [tablefield: numeric]
- The numeric attribute to calculate statistics on
* - **Additional creation options**
Optional
- ``OPTIONS``
- [string]
Default: '' (no additional options)
- Additional GDAL creation options.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Dissolved**
- ``OUTPUT``
- [same as input]
- The output multipart geometry layer (with dissolved
geometries)
Python code
...........
**Algorithm ID**: ``gdal:dissolve``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _gdaloffsetcurve:
Offset curve
------------
Offsets lines by a specified distance.
Positive distances will offset lines to the left, and negative
distances will offset them to the right.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Input layer**
- ``INPUT``
- [vector: line]
- The input line layer
* - **Geometry column name**
- ``GEOMETRY``
- [string]
Default: 'geometry'
- The name of the input layer geometry column to use
* - **Offset distance (left-sided: positive, right-sided: negative)**
- ``DISTANCE``
- [number]
Default: 10.0
-
* - **Offset curve**
- ``OUTPUT``
- [vector: line]
Default: ``[Save to temporary file]``
- Specify the output line layer. One of:
.. include:: ../algs_include.rst
:start-after: **file_output_types**
:end-before: **end_file_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Additional creation options**
Optional
- ``OPTIONS``
- [string]
Default: '' (no additional options)
- Additional GDAL creation options.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Offset curve**
- ``OUTPUT``
- [vector: line]
- The output offset curve layer
Python code
...........
**Algorithm ID**: ``gdal:offsetcurve``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _gdalonesidebuffer:
One side buffer
---------------
Creates a buffer on one side (right or left) of the lines in a line
vector layer.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Input layer**
- ``INPUT``
- [vector: line]
- The input line layer
* - **Geometry column name**
- ``GEOMETRY``
- [string]
Default: 'geometry'
- The name of the input layer geometry column to use
* - **Buffer distance**
- ``DISTANCE``
- [number]
Default: 10.0
-
* - **Buffer side**
- ``BUFFER_SIDE``
- [enumeration]
Default: 0
- One of:
* 0 --- Right
* 1 --- Left
* - **Dissolve by attribute**
Optional
- ``FIELD``
- [tablefield: any]
Default: None
- Field to use for dissolving
* - **Dissolve all results**
- ``DISSOLVE``
- [boolean]
Default: False
- If set, the result is dissolved.
If no field is set for dissolving, all the buffers are
dissolved into one feature.
* - **Produce one feature for each geometry in any kind of
geometry collection in the source file**
- ``EXPLODE_COLLECTIONS``
- [boolean]
Default: False
-
* - **One-sided buffer**
- ``OUTPUT``
- [vector: polygon]
Default: ``[Save to temporary file]``
- Specify the output buffer layer. One of:
.. include:: ../algs_include.rst
:start-after: **file_output_types**
:end-before: **end_file_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Additional creation options**
Optional
- ``OPTIONS``
- [string]
Default: '' (no additional options)
- Additional GDAL creation options.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **One-sided buffer**
- ``OUTPUT``
- [vector: polygon]
- The output buffer layer
Python code
...........
**Algorithm ID**: ``gdal:onesidebuffer``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**
.. _gdalpointsalonglines:
Points along lines
------------------
Generates a point on each line of a line vector layer at a distance
from start.
The distance is provided as a fraction of the line length.
Parameters
..........
Basic parameters
^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
:class: longtable
* - Label
- Name
- Type
- Description
* - **Input layer**
- ``INPUT``
- [vector: line]
- The input line layer
* - **Geometry column name**
- ``GEOMETRY``
- [string]
Default: 'geometry'
- The name of the input layer geometry column to use
* - **Distance from line start represented as a fraction of line length**
- ``DISTANCE``
- [number]
Default: 0.5 (middle of the line)
-
* - **Points along lines**
- ``OUTPUT``
- [vector: point]
Default: ``[Save to temporary file]``
- Specify the output point layer.
One of:
.. include:: ../algs_include.rst
:start-after: **file_output_types**
:end-before: **end_file_output_types**
Advanced parameters
^^^^^^^^^^^^^^^^^^^
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Additional creation options**
Optional
- ``OPTIONS``
- [string]
Default: '' (no additional options)
- Additional GDAL creation options.
Outputs
.......
.. list-table::
:header-rows: 1
:widths: 20 20 20 40
* - Label
- Name
- Type
- Description
* - **Points along line**
- ``OUTPUT``
- [vector: point]
- The output point layer
Python code
...........
**Algorithm ID**: ``gdal:pointsalonglines``
.. include:: ../algs_include.rst
:start-after: **algorithm_code_section**
:end-before: **end_algorithm_code_section**