Algorithms Include

Python Code Sample

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

ID-ul algoritmului se afișează atunci când treceți peste algoritmul din caseta instrumentelor de procesare. Dicționarul parametrilor furnizează valorile și NUMELE parametrilor. Pentru detalii despre rularea algoritmilor de procesare din consola Python, parcurgeți Utilizarea algoritmilor de procesare din consolă.

Output Types

Directory

  • Save to a Temporary Directory

  • Save to Directory

  • Skip Output

  • Save to a Temporary Directory

  • Save to Directory

File

  • Salvare într-un Fișier Temporar

  • Salvare în Fișier…

  • Skip Output

  • Salvare într-un Fișier Temporar

  • Salvare în Fișier…

Layer

  • Create Temporary Layer (TEMPORARY_OUTPUT)

  • Salvare în Fișier…

  • Save to Geopackage…

  • Save to Database Table…

The file encoding can also be changed here.

  • Create Temporary Layer (TEMPORARY_OUTPUT)

  • Salvare în Fișier…

  • Save to Geopackage…

  • Save to Database Table…

  • Append to Layer…

The file encoding can also be changed here.

  • Skip Output

  • Create Temporary Layer (TEMPORARY_OUTPUT)

  • Salvare în Fișier…

  • Save to Geopackage…

  • Save to Database Table…

The file encoding can also be changed here.

Extent Dropdown

Available methods are:

  • Calculate from layer…: uses extent of a layer loaded in the current project

  • Use map canvas extent

  • Draw on canvas

  • Enter the coordinates as xmin, xmax, ymin, ymax

Geometric predicates

Geometric predicates are boolean functions used to determine the spatial relation a feature has with another by comparing whether and how their geometries share a portion of space.

../../../_images/selectbylocation.png

Looking for spatial relations between layers

Using the figure above, we are looking for the green circles by spatially comparing them to the orange rectangle feature. Available geometric predicates are:

Intersect

Tests whether a geometry intersects another. Returns 1 (true) if the geometries spatially intersect (share any portion of space - overlap or touch) and 0 if they don’t. In the picture above, this will return circles 1, 2 and 3.

Contain

Returns 1 (true) if and only if no points of b lie in the exterior of a, and at least one point of the interior of b lies in the interior of a. In the picture, no circle is returned, but the rectangle would be if you would look for it the other way around, as it contains circle 1 completely. This is the opposite of are within.

Disjoint

Returns 1 (true) if the geometries do not share any portion of space (no overlap, not touching). Only circle 4 is returned.

Equal

Returns 1 (true) if and only if geometries are exactly the same. No circles will be returned.

Touch

Tests whether a geometry touches another. Returns 1 (true) if the geometries have at least one point in common, but their interiors do not intersect. Only circle 3 is returned.

Overlap

Tests whether a geometry overlaps another. Returns 1 (true) if the geometries share space, are of the same dimension, but are not completely contained by each other. Only circle 2 is returned.

Are within

Tests whether a geometry is within another. Returns 1 (true) if geometry a is completely inside geometry b. Only circle 1 is returned.

Cross

Returns 1 (true) if the supplied geometries have some, but not all, interior points in common and the actual crossing is of a lower dimension than the highest supplied geometry. For example, a line crossing a polygon will cross as a line (true). Two lines crossing will cross as a point (true). Two polygons cross as a polygon (false). In the picture, no circles will be returned.

Notes on algorithms

Atenționare

Geometry modification only

This operation modifies only the features geometry. The attribute values of the features are not modified, although properties such as area or length of the features will be modified by the clipping operation. If such properties are stored as attributes, those attributes will have to be manually updated.