QGIS Shortcuts

Find out which tool you want to use by:

descriptive examples
visual diagrams

What is your goal?

I want to…	Example:	Tool is:
Crop one layer to another without losing layer data.	Crop a map of all Oregon parks to be all park bounds that overlap the Portland area.	Vector Selection: Extract by location
Crop one layer to another and cut polygons if necessary.	Crop a map of parks to only be within the bounds of Portland city limits and cut parks into parts if necessary.	Vector Overlay: Intersection
Find features within a certain distance.	Find all houses within a floodplain.	Vector Selection: Extract by distance Vector Geometry: Buffer + Vector Selection: Extract by location
Find the features closest to…	Find the nearest school to each census tract.	Vector Analysis: Distance to nearest hub Vector Analysis: Shortest line between features
Find all features of a certain type.	Get only single family homes.	Vector Selection: Extract by attribute
Find features smaller/larger than…	Find parks larger than 5 acres.	Vector Selection: Extract by expression
Combine features based on a variable.	Combine industrial and commercial zones.	Vector General: Join attributes by… [multiple options]
Remove boundaries between features.	Merge Washington and Oregon into one location.	Vector Geometry: Dissolve
Get statistics for my data.	Find the average house price separated by race.	Vector Analysis: Statistics by categories
Count points in an area.	Count all the trees on a city map.	Vector Analysis: Count points in polygon
Calculate density from a raster picture.	Find the percent forest coverage of an area based on aerial photograph.	Raster Analysis: Zonal Statistics + Raster Analysis: Fill NoData Cells [to set zeroes]
Change the CRS.	My points show up in the ocean!	Vector General: Reproject Layer

Visual Guide to Overlapping Layers

When you have multiple vector layers, there are a variety of ways separate or combine the information in each of them. Here are examples of things you can do with a layers of polygons (counties and eco-regions), lines (rivers), and points (cities).

Shape Files

Oregon counties oregon ecoregions oregon rivers Oregon cities

Select Individual Features

Click individual features to select them and use the Clip tool to create a layer with just those features.

Combine Features

The Union tool will combine polygons of the same type.

selected counties, a plus, different selected counties, an arrow, all counties on one map

The Dissolve tool will turn individual polygons into a single combined polygon.

separate counties, an arrow, one shape of counties combined

Remove Features

You can select things and filter them out or you can use the Difference tool to remove areas of overlap.

all counties in Oregon, a plus, selected counties in Oregon, an arrow, a map with the selected counties missing

Select From Overlapping Areas

The Intersection tool will create a new layer from any portions of layers that overlap. The new layer will contain data and features from both previous layers.

selected counties in Oregon, a plus, selected ecoregions in Oregon, an arrow, a map with the only the overlapping areas

selected cities in Oregon, a plus, selected ecoregions in Oregon, an arrow, a map with the cities and the words "city + ecoregion information"

The Extract Attribute by Location tool has a similar function of creating a layer from overlapping areas, but it only keeps the features from the first input layer.

a map of cities, a map of ecoregions, a map of cities with the words "just city information"

Final layer is only the cities present in these eco-regions.

a map of ecoregions, a map of counties, a map of just the ecoregions that overlap with the counties

Final layer is only the eco-regions that overlap with the counties.

map of all counties, map of regions, map of counties that overlap regions

Final layer is all the counties that overlap with any part of the eco-regions.

Join Attributes from Different Layers

The Join Attributes by Location tool adds information from one layer to another layer based on their location.

a map of ecoregion, a map of counties, a map of counties with the words "counties labeled with ecoregions"

Final layer includes county and data and new columns for the eco-region the county falls in.

a map of rivers, a map of counties, a map of rivers with the words "rivered labeled by counties"

Final layer includes all the river data with new columns that say which county the rivers are in.

a map of counties, a map of rivers, a map of counties with the words "counties labeled with rivers"

Final layer includes all county data and new columns for river data. Since a county can have multiple rivers run through it, there are additional rows for counties with more than one river.

Find the Nearest Attribute

The Join Attributes by Nearest tool adds information from one layer to another layer based on location and adds columns to measure distance between them.

map of cities, map of rivers, map of cities with words "cites with distance to nearest river"

The final layer has a row for every city, new columns from the river file, and the distance between the city and the river.

Buffer

The Buffer tool adds polygon zone around a point, line, or other polygon.

a map of cities, a map with circles around the cities, a map with larger circles around the cities

You can set the width of the buffer by different units of measurement.

a map of cities, a map with blobs around any cities that are close to each other

The buffer can be combined with dissolve to create regions around feature type.

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Data @ Reed