Questions tagged [nearest-neighbor]

A technique for resampling raster data in which the value of each cell in an output raster is calculated using the value of the nearest cell in an input raster.

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38 views

Nearest neighbour analysis from existing Excel sheet

I learnt the Nearest Neighbor Analysis from QGIS Tutorials and Tips. The result of this analysis, see image below I know that after running the distance to nearest hub analysis, it produces hub lines ...
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Calculating number of points within certain radius for multi-type point patterns using R [closed]

I have two sets of points, A, and B, and they are defined in the same region. For each point of A, I want to calculate how many points of type A and B are within the circle, respectively(radius = r) ...
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24 views

ST_ClosestPoint() moves all points to one line instead of closest line

I have a line network and I've created evenly-spaced points along those lines. The problem is that the points are not exactly on the line so subsequent overlay operations will not work as expected. I'...
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173 views

Rockfall analysis (Nearest neighbor downhill) in QGIS

I am working on a rockfall guide for QGIS and I'm currently stuck on one of the stages. I currently at a point in the guide where I have two point layers one "rockfall release point"-layer and "...
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22 views

Nearest Neighbor Two Point Tables Return Line Geometry

I am looking to find the nearest neighbor between two point tables in PostGIS and return the ids of both along with the line geometry. I have been able to determine the distance for the nearest ...
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1answer
28 views

Spatial 1 to 1 join by proximity in sf and R?

I'm trying to join a Simple Feature of POINT geometry type to another Simple Feature of POLYGON geometry type using st_join and nngeo::st_nn as the person asking this other question also did. The ...
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20 views

Nearest Neighbour along a route instead of geographical displacement

Say that I have three layers as follows for a certain region: Line Layer representing roads Point Layer representing hotels Point Layer representing train stations Using QGIS is there a way in which ...
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1answer
63 views

ST_Distance does not give nearest node

I am trying to find the nearest point on the road network closest to a given point. I imported the road network into PostGIS from QGIS and am using the SQL window in QGIS DB Manager to query the road ...
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1answer
44 views

Distinct st_shortestline

I have 61 pts and numerous rds. I would like to find the shortest distance to the nearest road using st_shortestline. I need 61 unique line segments, one for each point to its nearest road. Instead I ...
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1answer
111 views

Calculating nearest neighbor within each polygon using QGIS?

I have 3 layers: world map divided into countries; layer of points representing cities; layer of points representing conflict events (e.g. firefight). My goal: For each city, calculate the nearest ...
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2answers
84 views

Calculating distance between multiple lines of points in QGIS?

I'm looking to calculate a distance from a sensor reading to that of the nearest sensor reading on a different sensor line, all held within the same points file. Ideally using QGIS. The image below ...
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31 views

NearestNeighbor producing bad quality tiles

I have been using Bicubic interpolation to render some basemaps because this produced good results. This is what I get when using Bicubic: However, when using Nearest Neighbor interpolation, a white ...
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33 views

Finding nearest 10 observations that occurred 2 years before original observation using ArcGIS Pro ModelBuilder?

I have a point sample of house sales (~42k points over 9 year period) with a date field(integer), and for each point I want to find the 10 nearest houses within a year of sale and also which were sold ...
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23 views

How to get Memory layer dispalyed in Vector Panel List using Pyqgis?

I have two point layer in my Project Centroid.shp and Nodes.shp.I have used Distance Matrix to find nearest Nodes point from Centroid Point. I have saved the output in FinalDistance.csv. The ...
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1answer
65 views

Error creating DEM with Nearest Neighbour tool in QGIS?

I have an issue when I am creating a DEM with the tool natural neighbour on QGIS. When I extract my data directly on Qgis I have no issue creating a DEM. My points are coming from different sources ...
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1answer
33 views

Neighborhood Analysis with ArcGIS Spatial Analyst to Calculate Percentage

I have a raster file where the cells (1 meter) are classified as 1 (forest) and 0 (non-forest). I would like to create another raster (1 meter) where each cell is given the percentage of cells within ...
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329 views

Combining st_join with st_nn to include all points within, as well as within a given distance of a polygon

This is a follow up to my earlier question (Spatial join in R - Adding points to polygons with multiple corresponding points). I have successfully joined a spatial points file to a polygon file in R ...
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1answer
90 views

Nearest Neighbor - return object ID in R

I have a csv file that contains the GPS coordinates of about 100 villages and their unique ID. I have an other csv file with the GPS coordinates of some potential destinations and their unique ID. I ...
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PostGIS - Nearest Neighbour Join to sum values

I have a table of polygons T1 and a second table of points P1 Each point has a value I want to sum the values of P1 for each T1, with P1 being the closest set of points to T1 At the moment the only ...
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1answer
147 views

Find the closest Point from a Point which contains the same attribute

I am trying to create python code to iterate through points on 1 layer and find the closest point on another layer (Road Chainages) based on attribute values. I need to limit the search to < 20m ...
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27 views

Seeking package/function in R that can help tag GPS coordinates of fauna sightings to nearest sampling point?

I have 1 dataset of animals sighted walking a survey, and I would like to tag them to the respective sampling points along a transect. Any idea what function/package in R can do that? Maybe ...
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1answer
504 views

Nearest Neighbor Analysis Results

I'm fairly new and entirely self-taught in using QGIS 3.4. I'm looking at turtle nest sites and trying to run a nearest neighbor analysis to analyze their distribution and establish whether or not ...
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1answer
381 views

Spatial join attributes based on closest point in PostGIS

I have two point tables from which I want to extract a value from one table to the other, based on the nearest distance of those two points. t1 t2 id | value id 1 | 100 1 ...
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1answer
47 views

How to find the closest stop point PostGIS

I have Point geometries created from lat,lon I loaded all the 10,000 stops in a certain city using gtfs i would like to query my db to find the closest stop reference to my point. the staypoint ...
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1answer
216 views

PostGIS -> LineString + PointZ = LineStringZ

DATA I have 2 tables in PostGIS: linestable with MultiLineString geom surveypointtable with Point + elevation attribute GOAL The goal is to rebuild the lines as 3D replacing line's vertices with ...
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154 views

SRTM/DEM 1m resolution (batymetri) to point [closed]

I have bathymetry data (1 huge data) = SRTM/DEM/FGDBRaster (0,9818m resolution pixel, floating, 32 bit, 45 GB size) and an alternative data (split into small pieces data) = same data but with 1m ...
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270 views

A line between point to nearest neighbour point using QGIS

I have a layer of points in QGIS which represent electric poles How do I create a polyline layer that would have lines running between the poles so it can represent the the electric cables that ...
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1answer
322 views

Efficient way to find nearest feature between huge postgres tables

I have two tables (g1 and g2), both with around two million features. I need to know for each feature in g1, which is the closest feature from g2, with a condition. Since they are both so huge, I also ...
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228 views

Excluding point from Nearest neighbor search once it's been matched using R?

I have two lists of addresses, List 1 and List 2. I want to find the nearest neighbors of the list--but without assigning more than one point to any point. So say point 1A is the nearest neighbor of ...
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2answers
168 views

Query takes very long time

I'm a newbie to POSTGIS and I wonder if someone could help me out. I have loaded all postal codes with their geographical coordinates (geography) and created an index on this coordinate. When I run ...
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1answer
149 views

Get closest road-segment to segmentized LineString points

So I have a table that stores a bunch of traffic counts for various road segments across the country. I'm regularly getting real-time location data from vehicles that are moving around a given region ...
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1answer
108 views

Query to return closest LineString given a Point [duplicate]

I have a road lines data in a table with field roads(id SERIAL ,the_line geometry(LineString,4326)) suppose an accident occurs in a middle or at any location in that waterline i want to stop the ...
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161 views

Interpolation in QGIS shows wrong output result [closed]

I have done interpolation (IDW and Nearest Neighbour) in QGIS. But interestingly the output shows the wrong result. The area where I have a huge number of points results in a lower Z value (it is ...
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132 views

Nearest Neighbour Analysis Or NN join

I have two Layer in my Project 1) Voronoi Layer which is constructed on point Layer 2) Building Layers which is represented as Polygon. The goal is to find the nearest node for every polygon (...
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1answer
72 views

No module named 'mmqgis'

I have two layers in my Project 1)Points Layers 2) Polygon Layer I need to apply nearest neighbour Analysis between point and Polygon, but i am unable to get . I tried the below code.I am using ...
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1answer
101 views

Constructing Voronoi Polgon and Applying Nearest neigbour in it

I am learning QGIS 3.XX and currently working on Voronoi Polygons. I have three layers Point layer Building Layer Population CSV file. These points layer are basically water tanks and building ...
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220 views

Geo-hash finding nearest neighbour with massively variable distance to actual nearest neighbour

I have a series of points in lat-long space, ranging from having their nearest neighbour very close to 1000s of km away. Say I do a geo-hash of these to a high precision, my search of nearest ...
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1answer
176 views

Optimizing a nearest neighbor search in PostGIS for a large dataset

The below code is working well for smaller datasets, however I want to use this with a 30 GB table. Every time I run it using the larger table I run out of SSD space, the table gets to 127 GB in size! ...
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2answers
505 views

Nearest Neighbor

We've got a table of approximately 300,000 points and would like to find the nearest neighbor (within 10km) to each point in the same table. The most efficient query we've found so far is below, but ...
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204 views

Find the nearest neighbour for points in one layer to points in another, then measure the distance

USING QGIS 2.18.19 with python console (planning to upgrade to the newest QGIS after this piece of programming) I am struggling with finding the correct pyQGIS coding for this. I have a shapefile ...
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1answer
149 views

For each row of GPS coordinates, get value from nearest road to coordinates and copy to said row using PostGIS? [closed]

I have two tables in my database; one contains a set of GPS coordinates of a car which have been converted to geom, and another containing Open Street Map road data, including the speed limit for most ...
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1answer
292 views

Nearest point on line from a point in PostGIS and its attribute value

Consider the following image; I have points (shown in blue circles) stored in my database with their geometry and an attribute value. Additionally, I have another table with User Points (yellow ...
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1answer
54 views

Get barrier edge id

I have a table of POINTs that represent barriers. I would like to be able to find the closest edge id on the edge graph so that I can have the routing algorithm ignore that edge (thus route around it)....
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1answer
153 views

QGIS 3.0.2 NNJoin doesn't complete. Crashes when close status bar

I have run a large spatial point to polygon join of 2 million points to 657 polygons. I used NNJoin so that the closest polygon will be assigned to a point if the point does not lie within one. The ...
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2answers
156 views

Nearest Neighbor search in PostGIS using cases

I am using the following PostGIS nearest neighbor query to determine how close a point is to an area (polygon) that has been flooded and it's working well: SELECT ST_AsText(ST_SetSRID(...
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2answers
831 views

How to UPDATE with LATERAL Nearest-Neighbour query?

Say I have table gps like: CREATE TABLE gps( gps_id serial primary key, measured_timestamp timestamp, geom Geometry(Point,4326), stop_id int --Null ); And I have a table of stops like: ...
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1answer
426 views

Merging overlapping polygons with original polygons in QGIS

I have a large vector shapefile dataset containing polygons, many of which overlap. I want to assign each overlapping section to one of the original overlapping polygons. E.g. if polygon A overlaps ...
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2answers
165 views

ST_ClosestPoint usage in QGIS 3.0

I try to use ST_ClosestPoint function to find the closest point to find the MultiLineString layer. My line layer (Reach) has 42 attributes and point layer (Stations) has 7 attributes. My code is: "...
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3answers
609 views

Projecting GPS point to point in closest pgrouting road (map matching)?

I'm quite new to PostGIS and pgRouting. I'm interested in doing a simple map matching. Precisely, finding the closest point in a given OSM road network. I’ve successfully imported the OSM network ...
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1answer
114 views

Intersection with closest point using PostGIS?

I'm trying to update the field of a point table with a value from a linestring one : update object_elevation set contour_elevation = c.contour from contours c where st_intersects(st_ClosestPoint(c....