23.1.13. Vector creation¶

Array of offset (parallel) lines
Array of translated features
Create grid
Create points layer from table
Generate points (pixel centroids) along line
Generate points (pixel centroids) inside polygon
Import geotagged photos
Points to path
Random points along line
Random points in extent
Random points in layer bounds
Random points inside polygons
Raster pixels to points
Raster pixels to polygons
Regular points

23.1.13.1. Array of offset (parallel) lines ¶

Creates copies of line features in a layer, by creating multiple offset versions of each feature. Each new version is incrementally offset by a specified distance.

Positive distance will offset lines to the left, and negative distances will offset them to the right.

../../../../_images/offset_lines_array.png

Fig. 23.21 In blue the source layer, in red the offset one¶

Allows features in-place modification

23.1.13.1.1. Parameters¶

Label	Name	Type	Description
Input layer	`INPUT`	[vector: line]	Input line vector layer to use for the offsets.
Number of features to create	`COUNT`	[number ] Default: 10	Number of offset copies to generate for each feature
Offset step distance	`OFFSET`	[number ] Default: 1.0	Distance between two consecutive offset copies
Segments	`SEGMENTS`	[number] Default: 8	Number of line segments to use to approximate a quarter circle when creating rounded offsets
Join style	`JOIN_STYLE`	[enumeration] Default: 0	Specify whether round, miter or beveled joins should be used when offsetting corners in a line. One of: 0 — Round 1 — Miter 2 — Bevel
Miter limit	`MITER_LIMIT`	[number] Default: 2.0	Only applicable for mitered join styles, and controls the maximum distance from the offset curve to use when creating a mitered join.
Offset lines	`OUTPUT`	[vector: line] Default: `[Create temporary layer]`	Specify the output line layer with offset 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.

23.1.13.1.2. Outputs¶

Label	Name	Type	Description
Offset lines	`OUTPUT`	[vector: line]	Output line layer with offset features. The original features are also copied.

23.1.13.1.3. Python code¶

Algorithm ID: qgis:arrayoffsetlines

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.2. Array of translated features ¶

Creates copies of features in a layer by creating multiple translated versions of each. Each copy is incrementally displaced by a preset amount in the X, Y and/or Z axis.

M values present in the geometry can also be translated.

Fig. 23.22 Input layers in blue tones, output layers with translated features in red tones¶

Allows features in-place modification

23.1.13.2.1. Parameters¶

Label	Name	Type	Description
Input layer	`INPUT`	[vector: any]	Input vector layer to translate
Number of features to create	`COUNT`	[number ] Default: 10	Number of copies to generate for each feature
Step distance (x-axis)	`DELTA_X`	[number ] Default: 0.0	Displacement to apply on the X axis
Step distance (y-axis)	`DELTA_Y`	[number ] Default: 0.0	Displacement to apply on the Y axis
Step distance (z-axis)	`DELTA_Z`	[number ] Default: 0.0	Displacement to apply on the Z axis
Step distance (m values)	`DELTA_M`	[number ] Default: 0.0	Displacement to apply on M
Translated	`OUTPUT`	[same as input] Default: `[Create temporary layer]`	Output vector layer with translated (moved) copies of the features. The original features are also copied. 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.

23.1.13.2.2. Outputs¶

Label	Name	Type	Description
Translated	`OUTPUT`	[same as input]	Output vector layer with translated (moved) copies of the features. The original features are also copied.

23.1.13.2.3. Python code¶

Algorithm ID: qgis:arraytranslatedfeatures

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.3. Create grid ¶

Creates a vector layer with a grid covering a given extent. Grid cells can have different shapes:

Fig. 23.23 Different grid cell shapes¶

The size of each element in the grid is defined using a horizontal and vertical spacing.

The CRS of the output layer must be defined.

The grid extent and the spacing values must be expressed in the coordinates and units of this CRS.

Default menu: Vector ▶ Research Tools

23.1.13.3.1. Parameters¶

Label	Name	Type	Description
Grid type	`TYPE`	[enumeration] Default: 0	Shape of the grid. One of: 0 — Point 1 — Line 2 — Rectangle (polygon) 3 — Diamond (polygon) 4 — Hexagon (polygon)
Grid extent	`EXTENT`	[extent]	Extent of the grid
Horizontal spacing	`HSPACING`	[number] Default: 1.0	Size of a grid cell on the X-axis
Vertical spacing	`VSPACING`	[number] Default: 1.0	Size of a grid cell on the Y-axis
Horizontal overlay	`HOVERLAY`	[number] Default: 0.0	Overlay distance between two consecutive grid cells on the X-axis
Vertical overlay	`VOVERLAY`	[number] Default: 0.0	Overlay distance between two consecutive grid cells on the Y-axis
Grid CRS	`CRS`	[crs] Default: Project CRS	Coordinate reference system to apply to the grid
Grid	`OUTPUT`	[vector: any] Default: `[Create temporary layer]`	Resulting vector grid layer. 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.

23.1.13.3.2. Outputs¶

Label	Name	Type	Description
Grid	`OUTPUT`	[vector: any]	Resulting vector grid layer. The output geometry type (point, line or polygon) depends on the Grid type.

23.1.13.3.3. Python code¶

Algorithm ID: qgis:creategrid

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.4. Create points layer from table ¶

Creates points layer from a table with columns that contain coordinates fields.

Besides X and Y coordinates you can also specify Z and M fields.

23.1.13.4.1. Parameters¶

Label	Name	Type	Description
Input layer	`INPUT`	[vector: any]	Input vector layer or a table.
X field	`XFIELD`	[tablefield: any]	Field containing the X coordinate
Y field	`YFIELD`	[tablefield: any]	Field containing the Y coordinate
Z field Optional	`ZFIELD`	[tablefield: any]	Field containing the Z coordinate
M field Optional	`MFIELD`	[tablefield: any]	Field containing the M value
Target CRS	`TARGET_CRS`	[crs] Default: `EPSG:4326`	Coordinate reference system to use for layer. The provided coordinates are assumed to be compliant.
Points from table	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	Specify the resulting point layer. 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.

23.1.13.4.2. Outputs¶

Label	Name	Type	Description
Points from table	`OUTPUT`	[vector: point]	The resulting point layer

23.1.13.4.3. Python code¶

Algorithm ID: qgis:createpointslayerfromtable

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.5. Generate points (pixel centroids) along line ¶

Generates a point vector layer from an input raster and line layer.

The points correspond to the pixel centroids that intersect the line layer.

../../../../_images/points_centroids.png

Fig. 23.24 Points of the pixel centroids¶

23.1.13.5.1. Parameters¶

Label

Name

Type

Description

Raster layer

INPUT_RASTER

[raster]

Input raster layer

Vector layer

INPUT_VECTOR

[vector: line]

Input line vector layer

Points along line

OUTPUT

[vector: point]

Default: [Create temporary layer]

Resulting point layer with pixel centroids. 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.

23.1.13.5.2. Outputs¶

Label	Name	Type	Description
Points along line	`OUTPUT`	[vector: point]	Resulting point layer with pixel centroids

23.1.13.5.3. Python code¶

Algorithm ID: qgis:generatepointspixelcentroidsalongline

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.6. Generate points (pixel centroids) inside polygon ¶

Generates a point vector layer from an input raster and polygon layer.

The points correspond to the pixel centroids that intersect the polygon layer.

../../../../_images/points_centroids_polygon.png

Fig. 23.25 Points of the pixel centroids¶

23.1.13.6.1. Parameters¶

Label

Name

Type

Description

Raster layer

INPUT_RASTER

[raster]

Input raster layer

Vector layer

INPUT_VECTOR

[vector: polygon]

Input polygon vector layer

Points inside polygons

OUTPUT

[vector: point]

Default: [Create temporary layer]

Resulting point layer of pixel centroids. 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.

23.1.13.6.2. Outputs¶

Label	Name	Type	Description
Points inside polygons	`OUTPUT`	[vector: point]	Resulting point layer of pixel centroids

23.1.13.6.3. Python code¶

Algorithm ID: qgis:generatepointspixelcentroidsinsidepolygons

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.7. Import geotagged photos ¶

Creates a point layer corresponding to the geotagged locations from JPEG images from a source folder.

The point layer will contain a single PointZ feature per input file from which the geotags could be read. Any altitude information from the geotags will be used to set the point’s Z value.

Besides longitude and latitude also altitude, direction and timestamp information, if present in the photo, will be added to the point as attributes.

23.1.13.7.1. Parameters¶

Label	Name	Type	Description
Input folder	`FOLDER`	[folder]	Path to the source folder containing the geotagged photos
Scan recursively	`RECURSIVE`	[boolean] Default: False	If checked, the folder and its subfolders will be scanned
Photos	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	Specify the point vector layer for the geotagged photos. 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.
Invalid photos table Optional	`INVALID`	[table] Default: `[Skip output]`	Specify the table of unreadable or non-geotagged photos. One of: Skip Output Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to PostGIS Table… The file encoding can also be changed here.

23.1.13.7.2. Outputs¶

Label

Name

Type

Description

Photos

OUTPUT

[vector: point]

Point vector layer with geotagged photos. The form of the layer is automatically filled with paths and photo previews settings.

Invalid photos table

Optional

INVALID

[table]

Table of unreadable or non-geotagged photos can also be created.

23.1.13.7.3. Python code¶

Algorithm ID: qgis:importphotos

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.8. Points to path ¶

Converts a point layer to a line layer, by joining points in an order defined by a field in the input point layer (if the order field is a date/time field, the format must be specified).

Points can be grouped by a field to distinguish line features.

In addition to the line vector layer, a text file is output that describes the resulting line as a start point and a sequence of bearings / directions (relative to azimuth) and distances.

23.1.13.8.1. Parameters¶

Label	Name	Type	Description
Input point layer	`INPUT`	[vector: point]	Input point vector layer
Order field	`ORDER_FIELD`	[tablefield: any]	Field containing the order to connect the points in the path
Group field Optional	`GROUP_FIELD`	[tablefield: any]	Point features of the same value in the field will be grouped in the same line. If not set, a single path is drawn with all the input points.
Date format (if order field is DateTime) Optional	`DATE_FORMAT`	[string]	The format to use for the `Order field` parameter. Specify this only if the `Order field` is of type Date/Time.
Paths	`OUTPUT`	[vector: line] Default: `[Create temporary layer]`	Specify the line vector layer of the path. 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.
Directory for text output	`OUTPUT_TEXT_DIR`	[folder] Default: `[Skip output]`	Specify the directory that will contain the description files of points and paths. One of: Skip Output Save to a Temporary Directory Save to Directory… The file encoding can also be changed here.

23.1.13.8.2. Outputs¶

Label	Name	Type	Description
Paths	`OUTPUT`	[vector: line]	Line vector layer of the path
Directory for text output	`OUTPUT`	[folder]	Directory containing description files of points and paths

23.1.13.8.3. Python code¶

Algorithm ID: qgis:pointstopath

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.9. Random points along line ¶

Creates a new point layer, with points placed in the lines of another layer.

For each line in the input layer, a given number of points is added to the resulting layer. A minimum distance can be specified, to avoid points being too close to each other.

23.1.13.9.1. Parameters¶

Label	Name	Type	Description
Input point layer	`INPUT`	[vector: line]	Input line vector layer
Number of points	`POINTS_NUMBER`	[number] Default: 1	Number of points to create
Minimum distance between points	`MIN_DISTANCE`	[number] Default: 0.0	The minimum distance between points
Random points	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	The output random points. 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.

23.1.13.9.2. Outputs¶

Label	Name	Type	Description
Random points	`OUTPUT`	[vector: point]	The output random points layer.

23.1.13.9.3. Python code¶

Algorithm ID: qgis:qgisrandompointsalongline

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.10. Random points in extent ¶

Creates a new point layer with a given number of random points, all of them within a given extent.

A minimum distance can be specified, to avoid points being too close to each other.

Default menu: Vector ▶ Research Tools

23.1.13.10.1. Parameters¶

Label	Name	Type	Description
Input extent	`EXTENT`	[extent]	Map extent for the random points
Number of points	`POINTS_NUMBER`	[number] Default: 1	Number of point to create
Minimum distance between points	`MIN_DISTANCE`	[number] Default: 0.0	The minimum distance between points
Target CRS	`TARGET_CRS`	[crs] Default: Project CRS	CRS of the random points layer
Random points	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	The output random points. 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.

23.1.13.10.2. Outputs¶

Label	Name	Type	Description
Random points	`OUTPUT`	[vector: point]	The output random points layer.

23.1.13.10.3. Python code¶

Algorithm ID: qgis:randompointsinextent

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.11. Random points in layer bounds ¶

Creates a new point layer with a given number of random points, all of them within the extent of a given layer.

A minimum distance can be specified, to avoid points being too close to each other.

Default menu: Vector ▶ Research Tools

23.1.13.11.1. Parameters¶

Label	Name	Type	Description
Input layer	`INPUT`	[vector: polygon]	Input polygon layer defining the area
Number of points	`POINTS_NUMBER`	[number] Default: 1	Number of points to create
Minimum distance between points	`MIN_DISTANCE`	[number] Default: 0.0	The minimum distance between points
Random points	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	The output random points. 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.

23.1.13.11.2. Outputs¶

Label	Name	Type	Description
Random points	`OUTPUT`	[vector: point]	The output random points layer.

23.1.13.11.3. Python code¶

Algorithm ID: qgis:randompointsinlayerbounds

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.12. Random points inside polygons ¶

Creates a new point layer with a given number of random points inside each polygon of the input polygon layer.

Two sampling strategies are available:

Points count: number of points for each feature
Points density: density of points for each feature

A minimum distance can be specified, to avoid points being too close to each other.

Default menu: Vector ▶ Research Tools

23.1.13.12.1. Parameters¶

Label	Name	Type	Description
Input layer	`INPUT`	[vector: polygon]	Input polygon vector layer
Sampling strategy	`STRATEGY`	[enumeration] Default: 0	Sampling strategy to use. One of: 0 — Points count: number of points for each feature 1 — Points density: density of points for each feature
Point count or density	`VALUE`	[number ] Default: 1.0	The number or density of points, depending on the chosen Sampling strategy.
Minimum distance between points	`MIN_DISTANCE`	[number] Default: 0.0	The minimum distance between points
Random points	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	The output random points. 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.

23.1.13.12.2. Outputs¶

Label	Name	Type	Description
Random points	`OUTPUT`	[vector: point]	The output random points layer.

23.1.13.12.3. Python code¶

Algorithm ID: qgis:randompointsinsidepolygons

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.13. Raster pixels to points ¶

Creates a vector layer of points corresponding to each pixel in a raster layer.

Converts a raster layer to a vector layer, by creating point features for each individual pixel’s center in the raster layer. Any nodata pixels are skipped in the output.

23.1.13.13.1. Parameters¶

Label	Name	Type	Description
Raster layer	`INPUT_RASTER`	[raster]	Input raster layer
Band number	`RASTER_BAND`	[raster band]	Raster band to extract data from
Field name	`FIELD_NAME`	[string] Default: ‘VALUE’	Name of the field to store the raster band value
Vector points	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	Specify the resulting point layer of pixels centroids. 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.

23.1.13.13.2. Outputs¶

Label	Name	Type	Description
Vector points	`OUTPUT`	[vector: point]	Resulting point layer with pixels centroids

23.1.13.13.3. Python code¶

Algorithm ID: qgis:pixelstopoints

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.14. Raster pixels to polygons ¶

Creates a vector layer of polygons corresponding to each pixel in a raster layer.

Converts a raster layer to a vector layer, by creating polygon features for each individual pixel’s extent in the raster layer. Any nodata pixels are skipped in the output.

23.1.13.14.1. Parameters¶

Label	Name	Type	Description
Raster layer	`INPUT_RASTER`	[raster]	Input raster layer
Band number	`RASTER_BAND`	[raster band]	Raster band to extract data from
Field name	`FIELD_NAME`	[string] Default: ‘VALUE’	Name of the field to store the raster band value
Vector polygons	`OUTPUT`	[vector: polygon] Default: `[Create temporary layer]`	Specify the resulting polygon layer of pixel extents. 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.

23.1.13.14.2. Outputs¶

Label	Name	Type	Description
Vector polygons	`OUTPUT`	[vector: polygon]	Resulting polygon layer of pixel extents

23.1.13.14.3. Python code¶

Algorithm ID: qgis:pixelstopolygons

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.

23.1.13.15. Regular points ¶

Creates a new point layer with its points placed in a regular grid within a given extent.

The grid is specified either by the spacing between the points (same spacing for all dimensions) or by the number of points to generate. In the latter case, the spacing will be determined from the extent. In order to generate a full rectangular grid, at least the number of points specified by the user is generated for the latter case.

Random offsets to the point spacing can be applied, resulting in a non-regular point pattern.

Default menu: Vector ▶ Research Tools

23.1.13.15.1. Parameters¶

Label	Name	Type	Description
Input extent (xmin, xmax, ymin, ymax)	`EXTENT`	[extent]	Map extent for the random points
Point spacing/count	`SPACING`	[number] Default: 100	Spacing between the points, or the number of points, depending on whether `Use point spacing` is checked or not.
Initial inset from corner (LH side)	`INSET`	[number] Default: 0.0	Offsets the points relative to the upper left corner. The value is used for both the X and Y axis.
Apply random offset to point spacing	`RANDOMIZE`	[boolean] Default: False	If checked the points will have a random spacing
Use point spacing	`IS_SPACING`	[boolean] Default: True	If unchecked the point spacing is not taken into account
Output layer CRS	`CRS`	[crs] Default: Project CRS	CRS of the random points layer
Regular points	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	Specify the output regular point layer. 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.

23.1.13.15.2. Outputs¶

Label	Name	Type	Description
Regular points	`OUTPUT`	[vector: point]	The output regular point layer.

23.1.13.15.3. Python code¶

Algorithm ID: qgis:regularpoints

import processing
processing.run("algorithm_id", {parameter_dictionary})

The algorithm id is displayed when you hover over the algorithm in the Processing Toolbox. The parameter dictionary provides the parameter NAMEs and values. See Using processing algorithms from the console for details on how to run processing algorithms from the Python console.