27.1.1. Cartography

27.1.1.1. Align points to features 

Calculates the rotation required to align point features with their nearest feature from another reference layer. A new field is added to the output layer which is filled with the angle (in degrees, clockwise) to the nearest reference feature.

Optionally, the output layer’s symbology can be set to automatically use the calculated rotation field to rotate marker symbols. If desired, a maximum distance to use when aligning points can be set, to avoid aligning isolated points to distant features.

Hint

This algorithm is designed for use cases like aligning building point symbols to follow the nearest road direction.

Allows features in-place modification of point features

Parameters

Label	Name	Type	Description
Input layer	`INPUT`	[vector: point]	Point features to calculate the rotation for
Reference layer	`REFERENCE_LAYER`	[vector: any]	Layer to find the closest feature from for rotation calculation
Maximum distance to consider Optional	`MAX_DISTANCE`	[number] Default: Not set	If no reference feature is found within this distance, no rotation is assigned to the point feature.
Angle field name	`FIELD_NAME`	[string] Default: ‘rotation’	Field in which to store the rotation value.
Automatically apply symbology	`APPLY_SYMBOLOGY`	[boolean] Default: True	Rotates the symbol marker of the features using the angle field value
Aligned layer	`OUTPUT`	[vector: point] Default: `[Save to temporary file]`	Specify the rotated output vector layer. One of: Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Outputs

Label	Name	Type	Description
Aligned layer	`OUTPUT`	[vector: point]	The point layer appended with a rotation field. If loaded to QGIS, it is applied by default the input layer symbology, with a data-defined rotation of its marker symbol.

Python code

Algorithm ID: native:angletonearest

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.

27.1.1.2. Combine style databases 

Combines multiple QGIS style databases into a single style database. If items of the same type with the same name exist in different source databases these will be renamed to have unique names in the output combined database.

Parameters

Label

Name

Type

Description

Input databases

INPUT

[file] [list]

Files containing QGIS style items

Objects to combine

OBJECTS

[enumeration] [list]

Types of style items in the input databases you would like to put in the new database. These can be:

0 — Symbols
1 — Color ramps
2 — Text formats
3 — Label settings

Output style database

OUTPUT

[file]

Default: [Save to temporary file]

Output .XML file combining the selected style items. One of:

Save to a Temporary File
Save to File…

Outputs

Label	Name	Type	Description
Color ramp count	`COLORRAMPS`	[number]
Label settings count	`LABELSETTINGS`	[number]
Output style database	`OUTPUT`	[file]	Output `.XML` file combining the selected style items
Symbol count	`SYMBOLS`	[number]
Text format count	`TEXTFORMATS`	[number]

Python code

Algorithm ID: native:combinestyles

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.

27.1.1.3. Create categorized renderer from styles 

Sets a vector layer’s renderer to a categorized renderer using matching symbols from a style database. If no style file is specified, symbols from the user’s current symbol library are used instead.

A specified expression or field is used to create categories for the renderer. Each category is individually matched to the symbols which exist within the specified QGIS XML style database. Whenever a matching symbol name is found, the category’s symbol will be set to this matched symbol.

If desired, outputs can also be tables containing lists of the categories which could not be matched to symbols, and symbols which were not matched to categories.

Parameters

Label	Name	Type	Description
Input layer	`INPUT`	[vector: any]	Vector layer to apply a categorized style to
Categorize using expression	`FIELD`	[expression]	Field or expression to categorize the features
Style database (leave blank to use saved symbols)	`STYLE`	[file]	File (`.XML`) containing the symbols to apply to the input layer categories. The file can be obtained from the Style Manager Share symbols tool. If no file is specified, QGIS local symbols library is used.
Use case-sensitive match to symbol names	`CASE_SENSITIVE`	[boolean] Default: False	If True (checked), applies a case sensitive comparison between the categories and symbols names
Ignore non-alphanumeric characters while matching	`TOLERANT`	[boolean] Default: False	If True (checked), non-alphanumeric characters in the categories and symbols names will be ignored, allowing greater tolerance during the match.
Non-matching categories Optional	`NON_MATCHING_CATEGORIES`	[table] Default: `[Skip output]`	Output table for categories which do not match any symbol in the database. One of: Skip Output Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.
Non-matching symbol names Optional	`NON_MATCHING_SYMBOLS`	[table] Default: `[Skip output]`	Output table for symbols from the provided style database which do not match any category. One of: Skip Output Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Outputs

Label	Name	Type	Description
Non-matching categories	`NON_MATCHING_CATEGORIES`	[table]	Lists categories which could not be matched to any symbol in the provided style database
Non-matching symbol names	`NON_MATCHING_SYMBOLS`	[table]	Lists symbols from the provided style database which could not match any category
Categorized layer	`OUTPUT`	[same as input]	The input vector layer with the categorized style applied. No new layer is output.

Python code

Algorithm ID: native:categorizeusingstyle

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.

27.1.1.4. Create style database from project 

Extracts all style objects (symbols, color ramps, text formats and label settings) from a QGIS project.

The extracted symbols are saved to a QGIS style database (XML format), which can be managed and imported via the Style Manager dialog.

Parameters

Label

Name

Type

Description

Input project (leave blank to use current)

Optional

INPUT

[file]

A QGIS project file to extract the style items from

Objects to extract

OBJECTS

[enumeration] [list]

Types of style items in the input project you would like to put in the new database. These can be:

0 — Symbols
1 — Color ramps
2 — Text formats
3 — Label settings

Output style database

OUTPUT

[file]

Default: [Save to temporary file]

Specify the output .XML file for the selected style items. One of:

Save to a Temporary File
Save to File…

Outputs

Label	Name	Type	Description
Color ramp count	`COLORRAMPS`	[number]	Number of color ramps
Label settings count	`LABELSETTINGS`	[number]	Number of label settings
Output style database	`OUTPUT`	[file]	Output `.XML` file for the selected style items
Symbol count	`SYMBOLS`	[number]	Number of symbols
Text format count	`TEXTFORMATS`	[number]	Number of text formats

Python code

Algorithm ID: native:stylefromproject

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.

27.1.1.5. Export atlas layout as image 

Exports the atlas of a print layout as image files (e.g. PNG or JPEG images).

If a coverage layer is set, the selected layout’s atlas settings exposed in this algorithm will be overwritten. In this case, an empty filter or sort by expression will turn those settings off.

Parameters

Basic parameters

Label	Name	Type	Description
Atlas layout	`LAYOUT`	[layout]	Layout to export
Coverage layer Optional	`COVERAGE_LAYER`	[vector: any]	Layer to use to generate the atlas
Filter expression	`FILTER_EXPRESSION`	[expression]	Expression to use to filter out atlas features
Sort expression Optional	`SORTBY_EXPRESSION`	[expression]	Expression to use to sort the atlas features
Reverse sort order Optional	`SORTBY_REVERSE`	[boolean]	Determines if sorting should be inverted. Used when a sort expression is provided.
Output filename expression	`FILENAME_EXPRESSION`	[expression] Default: ‘output_’\|\|@atlas_featurenumber	Expression for use to generate filenames
Output folder	`FOLDER`	[folder]	Destination folder where the images will be generated

Advanced parameters

Label	Name	Type	Description
Map layers to assign to unlocked map item(s) Optional	`LAYERS`	[enumeration] [layer]	Layers to display in the map item(s) whose contents are not locked
Image format	`EXTENSION`	[enumeration] Default: png	File format of the generated output(s). The list of available formats varies depending on OS and installed drivers.
DPI Optional	`DPI` Default: Not set	[number]	DPI of the output file(s). If not set, the value in the print layout settings will be used.
Generate world file	`GEOREFERENCE`	[boolean] Default: True	Determines if a world file should be generated
Export RDF metadata	`INCLUDE_METADATA`	[boolean] Default: True	Determines if RDF metadata (title, author, …) should be generated
Enable antialiasing	`ANTIALIAS`	[boolean] Default: True	Determines if antialiasing should be enabled

Outputs

Label	Name	Type	Description
Image file	`OUTPUT`	[file]	Image files generated by the atlas layout

Python code

Algorithm ID: native:atlaslayouttoimage

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.

27.1.1.6. Export atlas layout as PDF (multiple files)

NEW in 3.24

Exports the atlas of a print layout to multiple PDF files.

If a coverage layer is set, the selected layout’s atlas settings exposed in this algorithm will be overwritten. In this case, an empty filter or sort by expression will turn those settings off.

Parameters

Basic parameters

Label	Name	Type	Description
Atlas layout	`LAYOUT`	[layout]	Layout to export
Coverage layer Optional	`COVERAGE_LAYER`	[vector: any]	Layer to use to generate the atlas
Filter expression	`FILTER_EXPRESSION`	[expression]	Expression to use to filter out atlas features
Sort expression Optional	`SORTBY_EXPRESSION`	[expression]	Expression to use to sort the atlas features
Reverse sort order Optional	`SORTBY_REVERSE`	[boolean]	Determines if sorting should be inverted. Used when a sort expression is provided.
Output filename Optional	`OUTPUT_FILENAME`	[expression]	Name pattern of the PDF output files.
Output folder	`OUTPUT_FOLDER`	[folder]	Destination folder for the output PDF files.

Advanced parameters

Label	Name	Type	Description
Map layers to assign to unlocked map item(s) Optional	`LAYERS`	[enumeration] [layer]	Layers to display in the map item(s) whose contents are not locked
DPI Optional	`DPI` Default: Not set	[number]	DPI of the output file(s). If not set, the value in the print layout settings will be used.
Always export as vectors	`FORCE_VECTOR`	[boolean] Default: False	Determines if vectorial data should be left as vectors
Always export as raster `NEW in 3.28`	`FORCE_RASTER`	[boolean] Default: False	Forces all the items in the map to be rasterized. This parameter takes precedence over the `FORCE_VECTOR` parameter.
Append georeference information	`GEOREFERENCE`	[boolean] Default: True	Determines if a world file should be generated
Export RDF metadata	`INCLUDE_METADATA`	[boolean] Default: True	Determines if RDF metadata (title, author, …) should be generated
Disable tiled raster layer exports	`DISABLE_TILED`	[boolean] Default: False	Determines if raster should be tiled
Simplify geometries to reduce output file size	`SIMPLIFY`	[boolean] Default: True	Determines if geometries should be simplified to reduce output file size
Text export	`TEXT_FORMAT`	[enumeration] Default: 0	Determines if text should be exported as path or text objects. Possible options are: 0 - Always export text as paths (recommended) 1 - Always export texts as text objects
Image compression `NEW in 3.28`	`IMAGE_COMPRESSION`	[enumeration] Default: 0	Determines compression level of the image and how suitable the file could be for printing outputs or post-production in external applications. Possible options are: 0 - Lossy (JPEG) 1 - Lossless

Outputs

Label	Name	Type	Description
PDF file	`OUTPUT`	[file]	PDF file corresponding to the exported atlas layout

Python code

Algorithm ID: native:atlaslayouttomultiplepdf

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.

27.1.1.7. Export atlas layout as PDF (single file)

Exports the atlas of a print layout as a single PDF file.

If a coverage layer is set, the selected layout’s atlas settings exposed in this algorithm will be overwritten. In this case, an empty filter or sort by expression will turn those settings off.

Parameters

Basic parameters

Label	Name	Type	Description
Atlas layout	`LAYOUT`	[layout]	Layout to export
Coverage layer Optional	`COVERAGE_LAYER`	[vector: any]	Layer to use to generate the atlas
Filter expression	`FILTER_EXPRESSION`	[expression]	Expression to use to filter out atlas features
Sort expression Optional	`SORTBY_EXPRESSION`	[expression]	Expression to use to sort the atlas features
Reverse sort order Optional	`SORTBY_REVERSE`	[boolean]	Determines if sorting should be inverted. Used when a sort expression is provided.
PDF file	`OUTPUT`	[file] Default: [Save to temporary file]	Name (including path) of the output file. One of: Save to a Temporary File Save to File…

Advanced parameters

Label	Name	Type	Description
Map layers to assign to unlocked map item(s) Optional	`LAYERS`	[enumeration] [layer]	Layers to display in the map item(s) whose contents are not locked
DPI Optional	`DPI` Default: Not set	[number]	DPI of the output file(s). If not set, the value in the print layout settings will be used.
Always export as vectors	`FORCE_VECTOR`	[boolean] Default: False	Determines if vectorial data should be left as vectors
Always export as raster `NEW in 3.28`	`FORCE_RASTER`	[boolean] Default: False	Forces all the items in the map to be rasterized. This parameter takes precedence over the `FORCE_VECTOR` parameter.
Append georeference information	`GEOREFERENCE`	[boolean] Default: True	Determines if a world file should be generated
Export RDF metadata	`INCLUDE_METADATA`	[boolean] Default: True	Determines if RDF metadata (title, author, …) should be generated
Disable tiled raster layer exports	`DISABLE_TILED`	[boolean] Default: False	Determines if raster should be tiled
Simplify geometries to reduce output file size	`SIMPLIFY`	[boolean] Default: True	Determines if geometries should be simplified to reduce output file size
Text export	`TEXT_FORMAT`	[enumeration] Default: 0	Determines if text should be exported as path or text objects. Possible options are: 0 - Always export text as paths (recommended) 1 - Always export texts as text objects
Image compression `NEW in 3.28`	`IMAGE_COMPRESSION`	[enumeration] Default: 0	Determines compression level of the image and how suitable the file could be for printing outputs or post-production in external applications. Possible options are: 0 - Lossy (JPEG) 1 - Lossless

Outputs

Label	Name	Type	Description
PDF file	`OUTPUT`	[file]	PDF file corresponding to the exported atlas layout

Python code

Algorithm ID: native:atlaslayouttopdf

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.

27.1.1.8. Export print layout as image 

Exports a print layout as an image file (e.g. PNG or JPEG images)

Parameters

Basic parameters

Label

Name

Type

Description

Print layout

LAYOUT

[layout]

Layout to export

Image file

OUTPUT

[file]

Default: [Save to temporary file]

Name (including path) of the output file. One of:

Save to a Temporary File
Save to File…

Advanced parameters

Label	Name	Type	Description
Map layers to assign to unlocked map item(s) Optional	`LAYERS`	[enumeration] [layer]	Layers to display in the map item(s) whose contents are not locked
DPI Optional	`DPI` Default: Not set	[number]	DPI of the output file(s). If not set, the value in the print layout settings will be used.
Generate world file	`GEOREFERENCE`	[boolean] Default: True	Determines if a world file should be generated
Export RDF metadata	`INCLUDE_METADATA`	[boolean] Default: True	Determines if RDF metadata (title, author, …) should be generated
Enable antialiasing	`ANTIALIAS`	[boolean] Default: True	Determines if antialiasing should be enabled

Outputs

Label	Name	Type	Description
Image file	`OUTPUT`	[file]	Image file corresponding to the exported print layout

Python code

Algorithm ID: native:printlayouttoimage

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.

27.1.1.9. Export print layout as PDF 

Exports a print layout as a PDF file.

Parameters

Basic parameters

Label

Name

Type

Description

Print Layout

LAYOUT

[layout]

Layout to export

PDF file

OUTPUT

[file]

Default: [Save to temporary file]

Name (including path) of the output file. One of:

Save to a Temporary File
Save to File…

Advanced parameters

Label	Name	Type	Description
Map layers to assign to unlocked map item(s) Optional	`LAYERS`	[enumeration] [layer]	Layers to display in the map item(s) whose contents are not locked
DPI Optional	`DPI` Default: Not set	[number]	DPI of the output file(s). If not set, the value in the print layout settings will be used.
Always export as vectors	`FORCE_VECTOR`	[boolean] Default: False	Determines if vectorial data should be left as vectors
Always export as raster `NEW in 3.28`	`FORCE_RASTER`	[boolean] Default: False	Forces all the items in the map to be rasterized. This parameter takes precedence over the `FORCE_VECTOR` parameter.
Append georeference information	`GEOREFERENCE`	[boolean] Default: True	Determines if a world file should be generated
Export RDF metadata	`INCLUDE_METADATA`	[boolean] Default: True	Determines if RDF metadata (title, author, …) should be generated
Disable tiled raster layer exports	`DISABLE_TILED`	[boolean] Default: False	Determines if raster should be tiled
Simplify geometries to reduce output file size	`SIMPLIFY`	[boolean] Default: True	Determines if geometries should be simplified to reduce output file size
Text export	`TEXT_FORMAT`	[enumeration] Default: 0	Determines if text should be exported as path or text objects. Possible options are: 0 - Always export text as paths (recommended) 1 - Always export texts as text objects
Image compression `NEW in 3.28`	`IMAGE_COMPRESSION`	[enumeration] Default: 0	Determines compression level of the image and how suitable the file could be for printing outputs or post-production in external applications. Possible options are: 0 - Lossy (JPEG) 1 - Lossless
Export layers as separate PDF files	`SEPARATE_LAYERS`	[boolean] Default: False	If True, then a separate PDF file will be created per layer per map item in the layout. Additionally, separate PDF files may be created for other complex layout items, resulting in a set of PDF files which contain logical atomic components of the layout.

Outputs

Label	Name	Type	Description
PDF file	`OUTPUT`	[file]	PDF file(s) corresponding to the exported print layout

Python code

Algorithm ID: native:printlayouttopdf

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.

27.1.1.10. Extract labels 

NEW in 3.24

Extracts label information from a rendered map at a given extent and scale.

If a map theme is provided, the rendered map will match the visibility and symbology of that theme. If left blank, all visible layers from the project will be used. Extracted label information include: position (served as point geometries), the associated layer name and feature ID, label text, rotation (in degree, clockwise), multiline alignment, and font details.

Parameters

Basic parameters

Label	Name	Type	Description
Map extent	`EXTENT`	[extent]	Extent of the map to extract the labels from Available methods are: Calculate from layer…: uses extent of a layer loaded in the current project Calculate from layout map…: uses extent of a layout map item in the active project Calculate from bookmark…: uses extent of a saved bookmark Use map canvas extent Draw on canvas: click and drag a rectangle delimiting the area to take into account Enter the coordinates as `xmin, xmax, ymin, ymax`
Map scale	`SCALE`	[scale]	Extracted labels will be rendered using their properties set at this scale.
Map theme Optional	`MAP_THEME`	[maptheme]	A map theme displaying the layers to extract the labels from. If unset, labels of the currently visible layers are extracted.
Include unplaced labels Optional	`INCLUDE_UNPLACED`	[boolean] Default: True	Specify whether all overlapping labels should be extracted, including the conflicting (thus unplaced) ones.
Extracted labels	`OUTPUT`	[vector: point] Default: `[Create temporary layer]`	Specify the output vector layer for the extent(s). One of: Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Advanced parameters

Label

Name

Type

Description

Map resolution (in DPI)

Optional

DPI

Default: 96.0

[number]

Outputs

Label	Name	Type	Description
Extracted labels	`OUTPUT`	[vector: point]	Point vector layer representing the fetched labels. Each feature has attributes identifying its source (layer, feature ID) and the assigned labeling properties (text, font, size, rotation, …). A default style with labeling and null symbol is also applied to the layer. Warning Because some of the generated fields have name with more than 10 characters, using the ESRI shapefile format (`.SHP`) to store the output may lead to unexpected rendering while loading the layer in QGIS.

Python code

Algorithm ID: native:extractlabels

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.

27.1.1.11. Print layout map extent to layer 

Creates a polygon layer containing the extent of a print layout map item (or items), with attributes specifying the map size (in layout units, i.e. the reference map units), scale and rotation.

If the map item parameter is specified, then only the matching map extent will be exported. If it is not specified, all map extents from the layout will be exported.

Optionally, a specific output CRS can be specified. If it is not specified, the original map item CRS will be used.

Parameters

Basic parameters

Label

Name

Type

Description

Print layout

LAYOUT

[enumeration]

A print layout in the current project

Map item

Optional

MAP

[enumeration]

Default: All the map items

The map item(s) whose information you want to extract. If none is provided then all the map items are processed.

Extent

OUTPUT

[vector: polygon]

Default: [Create temporary layer]

Specify the output vector layer for the extent(s). One of:

Create Temporary Layer (TEMPORARY_OUTPUT)
Save to File…
Save to Geopackage…
Save to Database Table…

The file encoding can also be changed here.

Advanced parameters

Label

Name

Type

Description

Overrride CRS

Optional

CRS

[crs]

Default: The layout CRS

Select the CRS for the layer in which the information will be reported.

Outputs

Label	Name	Type	Description
Map height	`HEIGHT`	[number]
Extent	`OUTPUT`	[vector: polygon]	Output polygon vector layer containing extents of all the input layout map item(s)
Map rotation	`ROTATION`	[number]
Map scale	`SCALE`	[number]
Map width	`WIDTH`	[number]

Python code

Algorithm ID: native:printlayoutmapextenttolayer

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.

27.1.1.12. Set layer style 

Applies a provided style to a layer. The style must be defined in a QML file.

No new output are created: the style is immediately assigned to the layer.

Parameters

Label	Name	Type	Description
Input Layer	`INPUT`	[layer]	Input layer you want to apply the style to
Style file	`STYLE`	[file]	Path to the `.qml` file of the style

Outputs

Label	Name	Type	Description
	`OUTPUT`	[same as input]	The input layer with the new style assigned. No new layer is created.

Python code

Algorithm ID: native:setlayerstyle

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.

27.1.1.13. Topological coloring 

Assigns a color index to polygon features in such a way that no adjacent polygons share the same color index, whilst minimizing the number of colors required.

The algorithm allows choice of method to use when assigning colors.

A minimum number of colors can be specified if desired. The color index is saved to a new attribute named color_id.

The following example shows the algorithm with four different colors chosen; as you can see each color class has the same amount of features.

../../../../_images/topological_color.png — Fig. 27.1 Topological colors example

Parameters

Label	Name	Type	Description
Input layer	`INPUT`	[vector: polygon]	The input polygon layer
Minimum number of colors	`MIN_COLORS`	[number] Default: 4	The minimum number of colors to assign. Minimum 1, maximum 1000.
Minimum distance between features	`MIN_DISTANCE`	[number] Default: 0.0	Prevent nearby (but non-touching) features from being assigned equal colors. Minimum 0.0.
Balance color assignment	`BALANCE`	[enumeration] Default: 0	Options are: 0 — By feature count Attempts to assign colors so that the count of features assigned to each individual color index is balanced. 1 — By assigned area Assigns colors so that the total area of features assigned to each color is balanced. This mode can be useful to help avoid large features resulting in one of the colors appearing more dominant on a colored map. 2 — By distance between colors Assigns colors in order to maximize the distance between features of the same color. This mode helps to create a more uniform distribution of colors across a map.
Colored	`OUTPUT`	[vector: polygon] Default: `[Create temporary layer]`	Specify the output layer. One of: Create Temporary Layer (`TEMPORARY_OUTPUT`) Save to File… Save to Geopackage… Save to Database Table… The file encoding can also be changed here.

Outputs

Label	Name	Type	Description
Colored	`OUTPUT`	[vector: polygon]	Polygon vector layer with an added `color_id` column

Python code

Algorithm ID: qgis:topologicalcoloring

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.

27.1.1.14. Transfer annotations from main layer 

Transfers all annotations from the main annotation layer in a project to a new annotation layer. Items placement can then be adjusted within the layer stack.

Parameters

Label

Name

Type

Description

New layer name

LAYER_NAME

[string]

Default: ‘Annotations’

Name of the annotations layer to create

Outputs

Label	Name	Type	Description
New layer name	`OUTPUT`	[layer]	A layer with items from the main annotation layer

Python code

Algorithm ID: native:transferannotationsfrommain

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.