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Questions tagged [algorithm]

A mathematical procedure used to solve problems with a series of steps. Algorithms are usually encoded as a sequence of computer commands.

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2
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1answer
39 views

Perform Tile Index on Newly Created PDFs using PyQGIS

The python code below successfully performs the tile index algorithm on all PDF files stored in sub-folders named !pdf's within my V:Drive. A list of all paths to each PDF exported from QGIS is ...
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0answers
8 views

Getting Omniscape analysis ERROR: LinearAlgebra.LAPACKException(3)?

I am currently running landscape connectivity analysis with Omniscape, but I get this error : ERROR: LinearAlgebra.LAPACKException(3) Stacktrace: [1] chklapackerror at /builddir/build/BUILD/julia/...
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0answers
20 views

Performing Cayula Cornillon single image edge detection algorithm to detect ocean SST fronts in Google Earth Engine?

I am a newbie in programming. I am working with sst data to find ocean fronts in GEE, but to build the Cayula Cornillon algorithm as in the following paper. Cayula Cornillon. 1992. Edge detection ...
2
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1answer
57 views

How to calculate line complexity index

I'm wondering if there is any suitable algorithm that can I use to calculate line complexity index (or indicator)? By "line complexity" I mean how many bends (direction changes) that line contains and ...
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0answers
18 views

Drawing equal paths from geographic points?

I have 10'000 geographic points (POS), 10 salesmen, and one starting point. To avoid discrimination between salesmen, everyone should travel the same distance and the same number of points of sale. ...
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1answer
38 views

Calculate position to put box into another container?

there has a big box, and the big box already contains many small box, then should place a new small box into the container. How do I calculate a big enough space to place the small box? There ...
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3answers
64 views

Splitting Streets to Create Polygons?

I have a need to take all the streets belonging to a certain area (in OpenStreetMap) and split each street by each other and form polygons from the segments that result from the split operation. I do ...
2
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0answers
31 views

Splitting linestrings based on their curvature

I'm looking for a method to split linestrings based on their curvature, more precisely if part of them could be considered a street corner. For example in the screenshot below, I'd need to split the ...
2
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1answer
87 views

Adding new attribute field to processing output algorithm in PyQGIS?

I have a processing script that will carry out a selection by expression of the input layer, then do a join attributes by location with a join layer. The next stage will be to add a new field and ...
0
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1answer
24 views

qgis:deletecolumn in QGIS 3 graphical modeler

I want to use the algorithm qgis:deletecolumn in a graphical modeler. How do I have to fill the case Fields to delete : ["field1","field2"] "field1","field2" field1,field2 [field1,field2] And is ...
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0answers
48 views

Getting minimum distance of points with scalable algorithm

I have a number of geographical coordinates with latitudes/longitudes: id | name | lat | lon 1 | New York | 40.730610 | 74.0060 2 | Philadelphia | 75.1652 | 39.9526 3 |...
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0answers
44 views

Simplifying Multiple neighbouring Polygons, removing gaps and overlaps

My main goal is to simplify multiple polygons, avoiding overlaps and gaps between them. My initial approach was: Find intersections for each polygon so that I end up with an array of polygons, each ...
1
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1answer
102 views

Performing isochrone in PostGIS by pgRouting?

In pgr_drivingDistance for isochrones the person who answered, missed to say the explanation of the answer about what function used by him to get the output for isochrone. I want to do the same but I ...
3
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0answers
32 views

What is the complexity (big / little o) of the ArcGIS watershed delineation algorithm? [closed]

I'm curious about the complexity, in terms of Big or little O notation, of watershed delineation algorithms: More specifically, does the time required to perform a watershed delineation depend on the ...
2
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0answers
28 views

Seeking method for determining survey points?

I'm trying to write software to create a topographic map, my goal is to select several points of interest and create a minimal mapping that is inclusive of the points and interpolates the topography. ...
3
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0answers
74 views

How to create equidistant points along lines (network)?

I am trying to create points at every X meters along a set of lines that represent a network. As suggested in QChainage doesn't place points evenly along dissolved lines I managed to this ...
2
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1answer
364 views

Client-Side Polygon split

I wanted to know if there is a way to split a polygon using JavaScript. So I have a web map which uses Leaflet API, and the user needs to cut polygons which are shown in the map using a straight line. ...
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0answers
53 views

Seeking Python implementation of contiguity constrained clustering?

I'm looking for an example of Python implementation of contiguity constrained clustering algorithm. The task I want to perform is to reduce the number of administrative zones by grouping them into as ...
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0answers
113 views

QGIS Python AttributeError object has no attribute 'pushVersionInfo'

I am unable to use almost all of the processing toolbox features in QGIS. I keep getting the following Python error across multiple algorithms: AlgorithmDialog.py", line 208, in runAlgorithm self....
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0answers
29 views

Algorithm(s) for Sensor Footprint at limbs

Is anyone aware of algorithm(s) that have been developed for computing remotely sensed image footprints that handle body limbs? The limb is the edge of the body / atmosphere where only the blackness ...
2
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0answers
32 views

Algorithm “qgis:difference” returns multiple heterogeneous outputs

I use the qgis:difference algorithm but it returns multi-type outputs. Sometimes it's a QgsVectorLayer but sometimes a str such as : output_.... My question is : when the algorithm returns an empty ...
4
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1answer
131 views

Match linestrings using Fréchet distance

I have two datasets of roads (both in WGS84). One has nicely digitized geometries, but lack some of the attributes and the other has heeded attributes, but digitized terribly. I want to transfer ...
0
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1answer
33 views

How is IDW raster formed?

IDW algorithm says that it makes a grid and assigns value to each point in grid depending on the distance of separation. From this definition, it looks like the output is set of equally spaced points. ...
3
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1answer
73 views

PYQGIS 3 Using the ouptut from GRASS v.distance algorithm

I have a script which is trying to run v.distance on two existing shape files, buildings.shp which containing some polygons and singleasn.shp which contains a single point. This will be run from the ...
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1answer
144 views

What algorithm is used by the $geowithin operator of Mongodb

MongoDB can perform geospatial query such as finding restaurants inside region with the operator $geowithin. For example: db.places.find( { loc: { $geoWithin: { $geometry: { ...
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2answers
351 views

Finding algorithms of QGIS commands?

I'm looking for the algorithms (the math) used by QGIS but I can't find any documentation about it The ones I'm looking for are: Minimum bounding geometry (convex hull) Clip a polygon by a ...
3
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0answers
44 views

What is the name of the popular buffer algorithm?

There is a well-known algorithm that I believe is used for the "buffer" function in some GIS libraries and applications. I have a vivid memory of reading the paper that describes the algorithm and ...
1
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1answer
135 views

Get progression bar into PyQGIS 3 standalone script

When I run a treatment inside QGIS with Processing toolbox (native algorithms) I get a progression bar : Is there a way to use this percentage inside a standalone PyQGIS script? I searched in the ...
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0answers
38 views

Creating decision rules on pixel level in time series layer in R? [closed]

I am using Landsat 5, 7, 8 images and RStudio. My goal is to compute the disturbance in a given area using the Vegetation Change Tracker (VCT) algorithm. I would like to ask you if you could provide ...
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1answer
245 views

Run pyQGIS algorithm on selected features in layer

I try to run algorithms on layers but only on selected features with QgsProcessingFeatureSourceDefinition in a loop and then write the result with QgsVectorFileWriter : layer1 = QgsVectorLayer(path1, ...
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1answer
156 views

PyQGIS processing: Overwrite not possible

I have a QGIS plugin that runs the v.clean algorithm two times (first time snap, second break) on a chosen layer: output = self.dlg.directory.text() params_snap = { 'input' : input, ...
2
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1answer
117 views

PyQGIS Processing: “memory: not found”

I try to run a QGIS plugin in QGIS 3.4 that uses processing to execute algorithms in a row: params_snap = { 'input' : input, 'type' : 1, 'tool' : 1, 'threshold' : ...
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1answer
106 views

Using Google Encoded Polyline Algorithm Format with Oracle Database

Google's Encoded Polyline Algorithm Format is implemented in several GI tools. PostGIS e.g. has ST_AsEncodedPolyline and ST_LineFromEncodedPolyline functions. In contrast, Oracle Database has no ...
0
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1answer
137 views

How to get equidistant points from a linestring (geographical coordinates) [closed]

I want to resample geographical coordinates based on a specific number of values, let's say, 1663 for the following case: -78.0599088 -11.89402416 -78.04317744 -11.88622134 -78.0267798 -11.87700462 -...
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1answer
176 views

How to combine geometries and numbers in Google Earth Engine

Trying to combine coordinates (geometries) with their respective slope (numbers) in Earth Engine. I am quite lost as to how to go about doing this. I've tried using ee.Algoritm.Feature to add metadata ...
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0answers
65 views

Calculating closest distance from location to given route?

I want to calculate the closest distance from a location (lat/lon) to a given route. The route consists of approximately 20.000 location points. I could calculate the distance to every location point ...
0
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1answer
79 views

Seeking QGIS algorithm for Swapping land parcels/plots by property?

I've searched for a QGIS Algorithm for swapping plots in an area by land owners and I didn't find anything. Do you know something that did that? For example, in an area or in a town we have 2 big ...
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2answers
163 views

Listing multiple fields to be dropped at once in QGIS modeler?

I'm trying to drop more than one fields at once in QGIS 3 modeler on Microsoft Windows. I'm using the algorithm "Drop field(s)". What is the good syntax to list multiple fields to be dropped? Not ...
1
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1answer
108 views

Finding a boundary with a collection of lines and a point

Given a collection of lines and a point how can I discover the closest boundary around the point. In the image below A represents a collection of disconnected lines and B is the boundary I want to ...
0
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1answer
48 views

Scaling down lat/lon polygon?

I have a set of (lat,lon) coordinates that compose a polygon. Is there a straightforward method to get an analogous set of coordinates defining a smaller version of the polygon? For example, given ...
2
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0answers
66 views

How can I share with other users a preconfigured algorithm?

I´m creating a process in QGIS, and I make it work automatic. But, I´ve used a preconfigured algorithm in order to avoid selecting shapes every time you use the process. So, is there any way I can ...
4
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1answer
54 views

Seeking algorithms for DEM generation? [closed]

What are the different algorithms employed for the generation of a Digital elevation model from images captured using an unmanned aerial vehicle ?
2
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1answer
471 views

Can you auto-populate a field in Survey123 from another field by only pulling certain characters?

I have a field where the user inputs text Aa1Bb2Cc3 Am I able to auto populate another field by only populating the field with Bb or 3. Auto populate the field with characters [4:6] or just [9] ...
2
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1answer
89 views

Find QGIS algorithm path

According to Using QGIS3 Processing algorithms from standalone PyQGIS scripts (outside of GUI) I try to implement the existing "Split Lines with Lines" algorithm into a QGIS Plugin. To do this I need ...
1
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1answer
101 views

What algorithm was used for generation of this vector layer?

The second image is a raster layer and in the third image obtained vector layer is so accurate. What algorithm would have been employed? Normal methods doesn't give nearly equal vectorization. I ...
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2answers
200 views

Optimal tiling of polygon using ArcGIS Desktop?

I am trying to tile a polygon with a minimal number of fixed sized squares. Currently I am creating a fishnet over my polygon then spatially joining the squares that intersect the polygon. This is ...
2
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0answers
90 views

GIS Clustering with drawing predefined square area around points as cluster boundaries

I have a layer of points and I would like to create clusters where a predefined square area of 5km by 5km is the boundary for the cluster. Is there a way to iteratively draw square polygons around ...
3
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2answers
68 views

Can Ksp Algorithm(Shortest Path Algorithm) have a constraint that the suggested paths must include a particular node or link

I am using pgr_ksp algorithm to find out the shortest path between a startnode and endnode by creating a network topology between all the nodes. Pgr_ksp algorithm very well gives me all the shortest ...
3
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1answer
193 views

Algorithm “qgis:difference” doesn't work in pyQGIS 3

I try to use native algorithm difference of QGIS. But it seams it doesn't work like the others : parameters = {'INPUT': polygons['OUTPUT'], #from temporary layer created before 'OVERLAY'...
0
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1answer
199 views

Debugging Error: Algorithm gdal:dissolve not found in PyQGIS?

I have difficulties with the processing package. I try to run a simple QGIS dissolve in pyQGIS 3. When I run the line : from qgis.core import QgsVectorLayer import processing from processing.core....