Questions tagged [qgis-processing]

Spatial data processing framework that brings advanced analysis capabilities to QGIS.

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10 answers
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Missing Processing Tools in Vector Menu of QGIS

I'm missing all the usual processing tools in the Vector menu in QGIS 2.16 (e.g. Vector Overlay, Analysis, etc). They do appear in the processing toolbox but there's no sign of them in the Vector menu....
user77875's user avatar
  • 906
44 votes
3 answers
61k views

Ignoring invalid input features with Intersection tool in QGIS?

In QGIS 2.18, when I used the Vector > Geoprocessing Tools > Intersection tool, I was able to check an option which said "Ignore NULL geometries [optional]". Now I've downloaded QGIS 3.2 and that ...
Felipe D.'s user avatar
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42 votes
5 answers
4k views

Generating equal sized polygons along line with PyQGIS

I would like to create polygons along a line to use them for AtlasCreator in a next step. ArcMap has a tool called Strip Map Index Features. With this tool I can choose the height and width of my ...
Berlinmapper's user avatar
41 votes
3 answers
16k views

Using QGIS Processing algorithms from PyQGIS standalone scripts (outside of GUI)

I am writing a script which must work outside of QGIS GUI. I call some API functions from qgis.core but I would like to use the processing plugin. I am able to import processing with sys.path.append() ...
vidlb's user avatar
  • 699
37 votes
7 answers
46k views

Fixing geometry validity errors in QGIS 2

I am working on ownership data at a US county level. I have one shapefile per county that contains thousands of tax parcels. I need to dissolve the polygons representing parcels owned by the same ...
Bap's user avatar
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36 votes
5 answers
19k views

Identifying clusters in vector point data using QGIS?

I have a vector dataset of rural broadband data-points (how fast, etc.) and I'd like to explore if there are clusters of points with similar characteristics, and to plot polygons encompassing them. ...
Adrian's user avatar
  • 1,131
29 votes
1 answer
2k views

How to calculate distance to a feature with gdal_proximity?

I'm using gdal_proximity to find the distance to the nearest major river across the USA (lower 48 states). I've projected the NHD+ network flowlines to Conus Albers (epsg:5070), selected rivers with ...
R Rhodes's user avatar
  • 391
20 votes
3 answers
11k views

Getting layer extent using PyQGIS

I'm trying to write a processing script using grass r.neighbors algorithm for rasters. When you use the GUI for this algorithm, you can leave the GRASS layer extent field blanc to use the minimal ...
Clement's user avatar
  • 765
20 votes
2 answers
19k views

Accessing QGIS processing with PyQGIS

I want to access the explode lines function in Python outside of QGIS from a standalone script. What module do I have to load in order to use it? How can I access processing? from qgis.core import * ...
ustroetz's user avatar
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19 votes
3 answers
6k views

Import error for qgis.core when running OSGeo4w shell script

I've been trying, along with this post, to run a script in OSGeo4w Shell, outside of QGIS. But I get the following error: ImportError: No module named qgis.core I have also read the following ...
Joseph's user avatar
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17 votes
3 answers
9k views

How to load memory output from QGIS processing?

Many processing algorithms have an option to save output as memory. If ran from toolbox, this works fine, because you can tick the "Open output file after running algorithm" box. Looking at the ...
user avatar
17 votes
2 answers
31k views

Removing overlapping part of polygons using QGIS?

Here is what I'd like to achieve in QGIS. Is there a processing tool to remove the overlapping part of polygons? It does not matter which polygon gets clipped. It is also very important that they do ...
Enzoupi's user avatar
  • 323
15 votes
2 answers
16k views

Getting the output layer reference returned by Processing tool

After running Processing algorithm ending up with a layer by run or runAndLoadResults in QGIS 3, these methods return a result which is mostly a dictionary like {'OUTPUT': 'file_path'} etc. So, after ...
Kadir Şahbaz's user avatar
15 votes
3 answers
4k views

What is "Fix geometries" tool actually doing in QGIS?

Sometimes geometry's have to be fixed for further processing. So you can use "Fix geometries" and it will do the job for you without prompting. But I'm wondering, what the tool "Fix ...
MartinMap's user avatar
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14 votes
4 answers
29k views

Creating parallel lines at particular distance from lines which are part of a shapefile

I am using QGIS 2.18 . I have shapefile which contains multiple lines. After processing certain data processing , I need to draw parallel lines at different distances from existing lines. For example ...
Jitendra's user avatar
  • 169
14 votes
1 answer
3k views

What is the new alglist and alghelp in QGIS 3.0 Processing?

Accessing the new QGIS 3.0 processing scripts through the Python console is proving to be a challenge for me, especially since the old processing.alglist() and processing.alghelp() commands appear to ...
Nick_W's user avatar
  • 565
14 votes
1 answer
2k views

Why the order of imports matters in a standalone PyQGIS processing script?

I've come across a weird issue while running standalone PyQGIS processing scripts. The order of imports in the script affects its normal execution. You can reproduce the problem by opening a Python ...
Germán Carrillo's user avatar
13 votes
3 answers
21k views

Missing processing menu in QGIS

I'm sure there is a really simple explanation to this but haven't found any pointers on this forum or elsewhere. I seem to have lost the 'Processing' menu from QGIS and can't figure out how/why!? Any ...
marty_c's user avatar
  • 549
13 votes
2 answers
6k views

processing.runalg() throws "TypeError: catching classes that do not inherit from BaseException is not allowed"

Hi everyone I'm in some way new with PyQGIS and I've been trying to run a script in QGIS 3.0 without success (it prefectly ran in 2.18) and always get the same error: AttributeError: module '...
LE_Geomatica's user avatar
13 votes
2 answers
18k views

Why "Export as Python script" button is unaccessible in QGIS 3.0/3.1 Modeler by default?

In QGIS 3.0, "Processing Modeler" window has no "Export as Python script" button unlike QGIS 2.x. If you look at the codes (in DlgModeler.ui and ModelerDialog.py files), you see the code lines ...
Kadir Şahbaz's user avatar
13 votes
1 answer
6k views

Modeling iterative processes in QGIS 3

In the QGIS version 2.X, there was an Iterative Button from the algorithm also available for the algorithm used inside the processing modeller. Actually, I use version 3.2 and 3.4 and can not find it....
AndreasR's user avatar
  • 161
13 votes
3 answers
9k views

Divide a complex shapefile into a grid

I have a decently detailed shapefile with polygon/multipolygon features (the file is about 500mb). It's actually a shapefile of the entire world, with the features representing coastlines. I need to ...
Pris's user avatar
  • 1,251
13 votes
3 answers
3k views

Is it possible to use memory layers in QGIS processing algorithms?

I am building a QGIS plugin that connects to a MySQL database in the local network, and then adds a subset of one of the tables to an in-memory layer; the subset is based on data currency (only taking ...
alphabetasoup's user avatar
13 votes
1 answer
10k views

Clean way to cancel QGIS processing scripts from gui

I've written a QGIS processing script that carries out a closest facility analysis. Taking the complete input data set (20k adresses as start points, ~100 target points, OSM road network with ~13k ...
Jochen Schwarze's user avatar
12 votes
1 answer
17k views

Distinction between Difference and Clip tools in QGIS?

What is the primary distinction between the Difference and Clip geoprocessing tools in QGIS?
Arun's user avatar
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12 votes
3 answers
13k views

QGIS 2.14 standalone GRASS provider missing Msys folder, can't execute tools

In QGIS 2.12 and down, when one went about manually setting the GRASS provider folder paths, this was the way to do it In GIS 2.14 there is no Msys folder in the same path (...\apps\msys) or any ...
HDunn's user avatar
  • 8,616
12 votes
1 answer
2k views

Assigning shortcut to PyQGIS script in QGIS

Is it possible to assign a keyboard shortcut to a (custom or not...) script of the Processing Toolbox in QGIS? I have not found any information about it so far.
Snaileater's user avatar
  • 5,723
12 votes
1 answer
4k views

Exporting Processing Modeler as Python script in QGIS 3?

How do I export my model from Processing Modeler as .py so that I can edit its code? This does not seem as intuitive as in previous QGIS versions.
Mary Johnson's user avatar
12 votes
1 answer
1k views

Changing parameter values according to other parameter choice in Processing script using QGIS 3?

I couldn't find anything about this problem. Suppose to have the first parameters in a Processing script defined as an Enum: self.addParameter( QgsProcessingParameterEnum( ...
matteo's user avatar
  • 3,304
12 votes
2 answers
1k views

Processing modeler Output Order

I have a model running on the processing framework it produces a serie of vector layers as output(alt-0, alt-1, alt-2, alt-3, and so on). I have prepared the model keeping the order of these ...
Mattia's user avatar
  • 271
12 votes
1 answer
491 views

Create points at specified distance from each other in random fishnet's cells while being on linestrings

We have a land protocol where we receive a fishnet of 1x1 km cells. Some cells are randomly choosed. We need to put 4 points in each cell and these points have to be on a road too. The minimum ...
Nicolas Boisteault's user avatar
12 votes
0 answers
383 views

Processing post-execution script hook to clear scratch layers?

I've been cobbling together some Processing scripts for QGIS 2.18 (I'm not a fan of QGIS 3 scripts), and I keep running into one particular problem: my script creates a lot of scratch layers and they ...
Nick_W's user avatar
  • 565
11 votes
5 answers
28k views

Processing toolbox nowhere to be found

I have just downloaded the newest version of QGIS (3.2) and the processing toolbox is nowhere to be found. It says that it is now apart of the core package, but i cannot find it on anywhere on the ...
A.J. Reyes's user avatar
11 votes
2 answers
5k views

Adding ArcToolbox tool to QGIS?

I have been using a publicly available tool in ArcGIS called SPreAD-GIS. It is a series of python scripts that are "implemented as an ArcGIS toolbox" (with tbx file). I am new to QGIS. Is there a ...
Gary's user avatar
  • 111
11 votes
1 answer
6k views

Using processing.runalg in QGIS 3

I try to create a common extent for rasters in QGIS 2.99. Here is my script: import processing processing.runalg("script:unifyextentandresolution", "/qgis_data/rasters/Image2.tif; ...
Mustafa Uçar's user avatar
11 votes
3 answers
2k views

Creating QGIS processing script that adds sequence to unique identifier column in PostGIS

Can anybody help me to create a QGIS processing script that adds a sequence to an existing unique identifier column (type: integer) in PostGIS? This would be quite helpful, e.g. as a workaround for ...
eclipsed_by_the_moon's user avatar
11 votes
1 answer
6k views

Looking to do a one-side buffer with QGIS v2.18.9

I'm working on a project that requires a 30m buffer around a linear feature. The feature represents the coast and I need the buffer to show 30m inland from the line representing the coast. Is there a ...
Ayla Marie's user avatar
11 votes
3 answers
3k views

Summing up values of neighbouring polygons using QGIS?

I hope that you can help me with the following problem: I have a vector (polygon) layer. I would like to add an attribute to the layer that - for every polygon - sums the values of a specific field of ...
Alex's user avatar
  • 221
11 votes
2 answers
10k views

Importing QGIS Processing in stand-alone python script?

I want to write a few stand-alone scripts that use the processing toolbox of Qgis. I have read a few threads (here and here, e.g.) but couldn't find a working solution yet. Using Qgis 2.16.1 on ...
Stéphane Henriod's user avatar
11 votes
2 answers
1k views

What's the batched Refactor Fields tool "field mapping" syntax in QGIS?

In QGIS, there is this nice tool "Refactor Fields" in the Processing Toolbox : Using it on a single layer is fairly straightforward. However, when you plan on using it in a batch mode, one can see ...
gisnside's user avatar
  • 7,818
11 votes
2 answers
1k views

How to perform repetitive tasks in QGIS?

I am trying to do a treatment on many feature files, so I would like to automate it. In fact, I have one shapefile with the spatial distribution of some species, and one with vegetation type. I ...
Onesime's user avatar
  • 449
11 votes
2 answers
2k views

Couldn't load plugin 'processing' on Windows 7 64bit

I installed QGIS (2.0.1-Dufour Dufour, d94c044) using both the stand alone installer and the OSgeo4w installer and seem to have an issue with the processing plugin. At first I thought that there was a ...
GuidoS's user avatar
  • 1,174
11 votes
1 answer
1k views

r.mapcalc does not give output in QGIS

For a while now I have been trying to use r.mapcalc from the QGIS Processing Toolbox. However, the algorithm does not give me any output. I have tried several raster layers and different expressions, ...
narra89's user avatar
  • 465
10 votes
3 answers
6k views

Find nearest line feature from point in QGIS

I have a line feature set and point feature set. I want to get the nearest line feature from every point. For this, the line features are converted to point using "Extract Nodes" tool. Then ...
Souvik Sankar Mitra's user avatar
10 votes
4 answers
1k views

Finding closest points on another polygon

I have three layers: polygons (having a unique id) stops (having the polygon id it is laying on) (point) possibilities (having the polygon id it is laying on) (point) I now want to find the closest ...
MrXsquared's user avatar
  • 33.9k
10 votes
1 answer
6k views

Using in-memory vector layer with QGIS processing / SEXTANTE

I'm trying to run the qgis:clip algorithm from console, but am getting an error when using an in-memory layer as the overlay parameter. Is this to be expected, or am I doing something wrong? Code: ...
user avatar
10 votes
3 answers
3k views

Drawing boundary of set of points using QGIS?

I have a set of points which I would like to change into a polygon. I tried concave hull but do not get the intended polygon as you can see below, And when I use Denaulay Triangulation I need to ...
Stephen Jacob's user avatar
10 votes
2 answers
1k views

QGIS 2.14.6 Processing Extension, 'Polygonize' Tool missing

Just installed QGIS 2.14.6 64Bit from OSGEO4W installer. Processing extension Version is 2.12.99. As can be seen in the screenshot, I'm not able to switch to 'Advanced Interface' as usual in order to ...
Jochen Schwarze's user avatar
10 votes
2 answers
6k views

Tiling GeoJSON data?

I have a GeoJSON dataset of the following format (LineString features): { "type": "FeatureCollection", "crs": { "type": "name", "properties": { "name": "urn:ogc:def:crs:OGC:1.3:CRS84" } }, "...
q9f's user avatar
  • 2,176
10 votes
1 answer
2k views

Using memory layer for processing algorithms in QGIS 3

I would like to run a processing algorithms in QGIS3 with a memory vector layer as result. When I define the memory layer as shown in the following, I get the error Incorrect parameter value for ...
Sophie Crommelinck's user avatar

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