Vector menu¶

Vector menu provides a one-stop resource for many common vector-based GIS tasks. It provides a growing suite of spatial data management and analysis functions that are both fast and functional. These features are part of the processing framework. Note that some plugins can add other features so, in this chapter, only default features from processing framework will be listed.

Processing framework is automatically installed and, like any plugin, can be enabled and disabled using the Plugin Manager (see The Plugins Dialog). When enabled, the Processing plugin adds a Vector menu to QGIS, providing functions ranging from Analysis and Research Tools to Geometry and Geoprocessing Tools, as well as several useful Data Management Tools.

See QGIS processing framework for more information about the processing framework.

Analysis tools¶

Icon	Tool	Purpose
	Distance matrix	Measure distances between two point layers, and output results as a) Square distance matrix, b) Linear distance matrix, or c) Summary of distances. Can limit distances to the k nearest features.
	Sum line length	Calculate the total sum of line lengths for each polygon of a polygon vector layer.
	Points in polygon	Count the number of points that occur in each polygon of an input polygon vector layer.
	List unique values	List all unique values in an input vector layer field.
	Basic statistics for text field	Compute basic statistics (mean, std dev, N, sum, CV) on an input text field.
	Basic statistics for numeric field	Compute basic statistics (mean, std dev, N, sum, CV) on an input numeric field
	Nearest neighbor analysis	Compute nearest neighbor statistics to assess the level of clustering in a point vector layer.
	Mean coordinate(s)	Compute either the normal or weighted mean center of an entire vector layer, or multiple features based on a unique ID field.
	Line intersections	Locate intersections between lines, and output results as a point shapefile. Useful for locating road or stream intersections, ignores line intersections with length > 0.

Table tools 1: Default tools in Analysis group

Research tools¶

Icon	Tool	Purpose
	Random selection	Randomly select n number of features, or n percentage of features.
	Random selection within subsets	Randomly select features within subsets based on a unique ID field.
	Random points inside polygons	Generate pseudo-random points over a polygon layer (variable number of point or fixed number of point).
	Random points in extent	Generate pseudo-random points over a given extent.
	Random points in layer bounds	Generate pseudo-random points over bounds of a given input layer.
	Regular points	Generate a regular grid of points over a specified region and export them as a point shapefile.
	Vector grid	Generate a line or polygon grid based on user-specified grid spacing.
	Select by location	Select features based on their location relative to another layer to form a new selection, or add or subtract from the current selection.
	Polygon from layer extent	Create a single rectangular polygon layer from the extent of an input raster or vector layer.

Table Tools 2: Default tools in Research group

Geoprocessing tools¶

Icon	Tool	Purpose
	Convex hull(s)	Create minimum convex hull(s) for an input layer, or based on an ID field.
	Buffer with * fixed distance * distance field	Create buffer(s) around features * based on fixed distance * based on distance field
	Intersect	Overlay layers such that output contains areas where both layers intersect.
	Union	Overlay layers such that output contains intersecting and non-intersecting areas.
	Symmetrical difference	Overlay layers such that output contains those areas of the input and difference layers that do not intersect.
	Clip	Overlay layers such that output contains areas that intersect the clip layer.
	Difference	Overlay layers such that output contains areas not intersecting the clip layer.
	Dissolve	Merge features based on input field. All features with identical input values are combined to form one single feature.
	Eliminate sliver polygons	Merges selected features with the neighboring polygon with the largest area or largest common boundary.

Table Tools 3: Default tools in Geoprocessing group

Geometry tools¶

Icon	Tool	Purpose
	Check geometry validity	Check polygons for intersections, closed holes, and fix node ordering. You can choose the engine used by the in the options dialog, digitizing tab Change the Validate geometries value. There is two engines: QGIS and GEOS which have pretty different behavior. Another tools exists which shows different result as well: Topology Checker plugin and ‘must not have invalid geometries’ rule.
	Export/Add geometry columns	Add vector layer geometry info to point (XCOORD, YCOORD), line (LENGTH), or polygon (AREA, PERIMETER) layer.
	Polygon centroids	Calculate the true centroids for each polygon in an input polygon layer.
	Delaunay triangulation	Calculate and output (as polygons) the Delaunay triangulation of an input point vector layer.
	Voronoi polygons	Calculate Voronoi polygons of an input point vector layer.
	Simplify geometry	Generalize lines or polygons with a modified Douglas-Peucker algorithm.
	Densify geometry	Densify lines or polygons by adding vertices.
	Multipart to singleparts	Convert multipart features to multiple singlepart features. Creates simple polygons and lines.
	Singleparts to multipart	Merge multiple features to a single multipart feature based on a unique ID field.
	Polygons to lines	Convert polygons to lines, multipart polygons to multiple singlepart lines.
	Lines to polygons	Convert lines to polygons, multipart lines to multiple singlepart polygons.
	Extract nodes	Extract nodes from line and polygon layers and output them as points.

Table Tools 4: Default tools in Geometry group

Poznámka

The Simplify geometry tool can be used to remove duplicate nodes in line and polygon geometries. Just set the Simplify tolerance parameter to 0 and this will do the trick.

Data management tools¶

Icon	Tool	Purpose
	Define current projection	Specify the CRS for shapefiles whose CRS has not been defined.
	Join attributes by location	Join additional attributes to vector layer based on spatial relationship. Attributes from one vector layer are appended to the attribute table of another layer and exported as a shapefile.
	Split vector layer	Split input layer into multiple separate layers based on input field.
	Merge shapefiles to one	Merge several shapefiles within a folder into a new shapefile based on the layer type (point, line, area).
	Create spatial index	Create a spatial index for OGR- supported formats.

Table Tools 5: Default tools in Data management group