Questions tagged [union]
In set theory, the union (denoted by ∪) of a collection of sets is the set of all distinct elements in the collection. It is one of the fundamental operations through which sets can be combined and related to each other.
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How to self union multipolygon layer a GeoDataFrame?
I need to perform a union operation inside a single layer. In Qgis there is an option not to select the second layer, but I can't figure out how to do it in geopandas?
Example:
Plots are red, zones ...
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Merge polygons that overlap into a multipart polygon while maintaining the original geometries/look
Overall, I want to display an index map that shows nautical charts and their corresponding inset charts. The majority of the time these insets lay directly on top of the "parent" chart in a ...
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Merging layers and excluding some of the products
When merging two layers of polygons so that they produce a third layer where no polygon contains another polygon, I find that the product contains some very small polygons, almost too small to see.
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Union tool problem (QGIS 3.22)
I used the Union tool for land use change analysis (From 1990 to 2000) but somehow the tool didn't work properly. I've attached a screenshot (first image) to show the problem. There are many ...
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PostGIS concatenating tables with different SRIDs side-effects for area
I am quite new to Postgres/PostGIS and have an open question regarding 'mixing' tables with different SRIDs.
I know this is generally not recommended, but in my case, I will already be required to ...
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How to combine buffered rivers and landcover type in earth engine to get union?
I want to pull one cover type from an image collection (NLCD) and combine it with buffered river data, a feature collection, with the result being a binary image containing the union or sum of the two....
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Cutting layer multiple times using top and bottom of other polygons QGIS
I have two "groups" of layers:
One layer (crosshatch) represents all of one type of data and then I have multiple (65) individual polygons representing another type of data (colored). The ...
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QGIS sum attribute values of overlapping line segments
This is sort of follow-up to this thread. Not sure how I got it working a year ago, but now I'm across the same issue again. Here is a clean dataset which I believe is correct. It contains overlapping ...
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Error 160196 union tool in ArcGIS Pro
I am trying to do union by using Union tool on my feature classes in ArcGIS Pro. The layers that I want to do union, are the results of the buffer 500m that I did on them. I have about 23 layers, but ...
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Creating unique ID for overlapping polygons in QGIS
In QGIS I created a union from a layer that had a lot of overlapping polygons. In the union layer, I used the Field Calculator (see the formula I used below) to count how many overlaps there were, as ...
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Using %n% inline variable as %n%-1 with Iterate Feature Classes iterator
I am new to ArcGIS Pro and have just a "Basic" license. I have no Python coding experience.
I am trying to make a ModelBuilder tool that will Union multiple feature classes (as little as two ...
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Getting percentage of parcels covered by slope polygon file using ArcGIS Pro without using Identity?
I've read the other similar stack questions and they weren't helpful, as in the processes didn't work or there was some ambiguous field references that may have contributed to my confusion and error.
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'union' between spatial polygons and spatial points in R
I have a gridded map shapefile with grid identifier cells (gid).
dput(head(grid))
structure(list(gid = c("183253", "183254", "183255", "183256",
"183258&...
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Creating Virtual Layer as union of multiple layers with same schema in QGIS
I have a Layer Group surveyor with lots of layers (shapefiles) with seemingly random names, and with identical schemas. I would like to combine them all to one layer; preferably with a Virtual Layer. ...
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Identify objectID of multiline to connect them in ArcPy
I have two sheets; in each there is a road network, but drawn by different people. Now I want to connect those lines that are intersected by the index sheets
as I shown below, but what I found is some ...
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Move values from united columns (union)
I am looking for a way to move values from united columns (union).
Using the Union command, I have merged several cleansed layers. Each source layer has the same columns (topic). Using the Union ...
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QGIS: Union: Could not add MultiStringZ object to MultiPolygonZ layer
I made some models in QGIS, mostly with the algorithms Union, Aggregate and Field Calculator while also using Fix geometries en Multipart to Singlepart at the start.
My output layer contains 7099 ...
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Why is my ST_Union output disproportionately large?
I have two multi-polygon geometry tables (see the figures below) in my PostGIS database and I would like to create a union of these two tables. They are ~12mb and ~1mb in size. However, the union of ...
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Union tool results in error: "GEOS geoprocessing error: intersection failed"
I am trying to use union processing on a number of overlapping polygons (approx 50-100) in the same layer. This raises the error "GEOS geoprocessing error: intersection failed", without any ...
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Using Union tool over MultiLineString in polygons layer in QGIS
I created a polygons layer in QGIS 3.22.2 by creating circular buffers around points.
I need to Union them by intersecting the overlapping parts. After running for several hours, the Union tool gives ...
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Polygon Union not working in QGIS
I am completely new to QGIS, so this issue might be really easy but I'm at a total loss on how to proceed.
I am attempting to combine datasets in QGIS utilizing the Polygon Union command, but am ...
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Multiple Unions & Dissolve for Buffers
I'm a new user of QGIS 3.10.4.
I need to create contours on maps using buffer, union and dissolve functions in QGIS. The buffers will be from multiple points.
Is there any way I can unionize and ...
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QGIS Union is slow. How to speed up or which alternative to use, creating the same output?
I have two polygon layers which I want to union. One layer (1) is just one big feature, the other (2) contains 250’000+ features. Layer 1 was created this way: Several polygons --> fix geometry --&...
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How to get union of multiple linestrings and polygons in Google Earth Engine?
I want to get the union of a list of multiple LineStrings and Polygons. The variable geoLeyte contains this list, but if I want to use the .dissolve() attribute, it gives an error. Who could help me?
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How to get union of multiple polygons in Google Earth Engine?
I would like to get the union of m (m is variable) different (multi)polygons in Google Earth Engine. The attribute .union() only works with two polygons. See example below for what I have till now.
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Merging two shapefiles with disparate attributes and keeping attributes of both using QGIS
I have two shapefiles of NYC--one of city council districts and another shapefile of the census blocks inside NYC. I want to merge these two shapefiles so that I can see what blocks lie inside of each ...
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ArcMap adjacency dissolve question - based on missing data in YR field
In my polygon shapefile, that was provided by a govt agency, there are thousands of records with DATAYR=0 which is entry error.
How do I dissolve/merge/union (doesn’t matter which operation) where ...
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PostGIS - ST_Union + ST_Difference create extra line segment
Very similar to this question
I have two multipolygons, which touch/overalp each over. please see this link for the multipolygon #1 and multipolygon #2
multipolygon #1
multipolygon #2
I ran st_union ...
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Compound contiguous links to lines in a network and find isolated lines
I want to compound the red and green links (lines between the poinst) to one or more lines. I need it to finde the green links that not touching the red lines in my network.
Step 1: compound touching ...
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Union multiple vector layers in QGIS
When combining two layers the "Union" tool works fine, and I have used Union several times: A + B => AB, then AB + C => ABC, then ABC + D => ABCD, and then ABCD + E => ABCDE and ...
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Transform GeoJSON shape with 2 requirements
We have this shape in GeoJSON:
https://gist.github.com/panchicore/0324b0e366211c3d907b1c42f54db9c9
And the expected output is:
Outer side (frontiers) sticks to its country frontiers (given the ...
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Getting the 'composite' of two polygon layers
I have two table of polygons, and I want to 'flatten' them into one table, and have the result tell me which areas are in one table of polygons, which in the other table of polygons, and which are in ...
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Classifying a shapefile after a union
I am trying to classify the Electoral Divisions of Ireland into their land use. To do this, I have obtained the Electoral Divisions shapefile (there are over 3000 polygons), and the Corine Land Cover (...
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Does UNION in PostGIS check for distinct geometries, or only other fields?
I've been getting some funny behaviour from UNION vs. UNION ALL when combining two tables in PostGIS, so just wanted to check:
Does UNION include a check for duplicate geometries when determining rows ...
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Convert lines to polygons, but closing the lines first (topographic lines not closed)
I have a topographic layer for a country. I want to select topographic lines of a certain altitude and transform the lines to polygons. All work fine except one thing: since the lines of the ...
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Looking for a Tool, that allows me to "Union" many overlapping layers, while prioritizing some to overwrite the others in ArcGIS
I am currently working on a project where I analyze the contents of a 500m buffer around several sample points.
Foundation for those informations are multiple shape file layers, which, alltogether, ...
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Union of multiple shapefiles (polygons) in ArcMap creates random vertical and horizontal lines (sections) in output
I have made a union of 4 features (polygon shapefiles) in ArcMap. However in the final output it has made random completely vertical/horizontal lines/sections in the final union. So it should look ...
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Getting all of combinations of features found on two layers using QGIS
This is a problem that seems like it should be simple, but it's a little difficult to explain. I have two polygon layers, each with a few hundred features (specifically the districts of England and ...
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pyqgis 3 Union multiple layers using temporary layers
I would like to use the tool "Union" to union 3 different layers. This tool unfortunately can union only 2 layers so I have to run it twice.
First I run it to union the layers "Layer1&...
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Using Union in ArcGIS Pro
I cannot see how Union is being used; why in this instance and whether it produces the desired results.
I am posting the procedure for some clarity. I don't understand the selection its asking for ...
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Union of shapefiles to generate composite shapefile with overlap frequency count for each polygon
I'm new to QGIS, making the switch from ArcMap. I have 5 shapefiles of polygons representing 5 years of insect defoliation. I need to overlay the 5 years and create a new composite shapefile that is a ...
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Joining (merge, union) non-overlapping vector polygons with QGIS
I look for a solution how I can join several polygons that do not overlap with each other and have no common sides, by creating a new polygon. That is, it should be an output polygon covering the &...
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Finding details of both overlapping shapes using ArcGIS Pro without Advanced level license
After Understanding Union analysis output using single feature class with overlapping polygons in ArcGIS Pro I now have a better understanding of that tool.
However, I have a single polygon Feature ...
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Understanding Union analysis output using single feature class with overlapping polygons in ArcGIS Pro
I have a single polygon Feature class with about 33,000 shapes. I'm looking for overlaps.
I want to be able to say "Shape x overlaps with Shape y and Shape z"
So the UNION analysis tool ...
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Count overlapping features using Geopandas
Is there a way to easily count overlapping polygons using Geopandas, the same way as the ArcGIS Pro Count Overlapping Features works?
So far my approach was to do union overlay and then dissolve with ...
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QGIS Union: Could not add feature with geometry type GeometryCollection to layer of type MultiPolygon
I overlay several Shapefile layers with Vector > Geoprocessing Tools > Union in QGIS. The first five layers do work. However, when I'm trying to add another layer I receive the following error ...
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Merging and deleting with priority overlapping polygons in QGIS
I have two shapefiles with polygons: one is regions for a country and the other is the protected areas inside that country.
I have merged these two polygons with Union, but the regions and protected ...
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Are there limits on the number of unique polygons created by the QGIS Union tool?
Is there a limit on the number of polygons that the Union tool will compute? I have overlapping radii from a variety of sources pictured below, but the tool continues to give me an "GEOS ...
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Why use st_union after st_combine with sf?
The documentation of the st_union function of sf is not clear (for me!) on one point: what are the action and result of the function when applied to an sfc with a single feature, with the parameter ...
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Merging two multipolygon tables into one and afterwards dissolving boundaries using PostGIS
I am trying to merge two multipolygon tables into one and at the same time - in the same query - dissolve the boundaries between the polygon districts using postgis.
The two tables are the red ...
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