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.

Filter by
Sorted by
Tagged with
1
vote
1answer
36 views

st_write fails for object created with st_difference using R?

Using publicly available sea area shapefiles bahamas: http://www.marineregions.org/gazetteer.php?p=details&id=8404 ("eez.zip") watl: http://www.marineregions.org/gazetteer.php?p=details&id=...
0
votes
0answers
14 views

How to do a union and specify that polygons must be greater than a certain area (e.g. 0.1 acres or greater)

I am doing a Union (or possibly an identity) of several polygon layers. I want to the result to contain only polygons .05 acres or greater, but do not want to eliminate any area. How do I ...
1
vote
0answers
17 views

How to recognize original group from unified set of polygons in R

I have simple question. How can I know the original group after apply z = sf::st_union(x, y)? I have 2 sets: length(x[[1]]) = 4253, length(y[[1]]) = 91. Finally, I have z of lenght 411 but don't know ...
1
vote
1answer
22 views

Attribute table After Union

I did a union of 2 layers, which technically represent the same thing but one is the updated version. This means that there is a common field in both, lets call it A. After I did the union, I opened ...
1
vote
1answer
11 views

ArcMap: Combining County Polygons for 3 separate states into one layer with attributes

I have 3 separate layers with the counties for 3 separate states: WA, OR, & ID. I want to combine them into one layer "Counties" so they all share an attribute table with the same fields. I am ...
2
votes
1answer
47 views

Dividing/tiling input features in FME, processing independently and fanning out the output by tile

I have two heavy-weight polygon feature classes that I want to union and then calculate some area-weighted average of one attribute for each aggregate (say parcel polygons, which is one of the inputs) ...
2
votes
1answer
40 views

QGIS (merging, dissolve, union) lines of same name

I have street data where roads are segmented for no particular reason. I want to merge, dissolve or union whatever seems fit to make a single flat line. I H have tried above processes in QGIS but ...
1
vote
1answer
55 views

Union, merge, intersection, join layers - logical difference and clear explanation for QGIS

I note that there are answers available on the difference between join and merge (e.g., Difference between 'join' and 'merge'?) that link to ArcGIS resources as a reference. However, I ...
0
votes
1answer
54 views

Cascading union OGR Multipolygons?

I have 2 OGR Multipolygons that intersect, hence I want to cascade Union them. I tried this but it returns me empty and doesn't union it. Seems this works only on Polygons and not Mul;tipolygons. What'...
0
votes
2answers
104 views

Dissolve only overlapping polygons in R using sf

I extracted information from open street map that contains many polygons, some of them overlapping. I want to union all polygons that overlap with other polygons. This question has been asked before ...
2
votes
1answer
56 views

Why does fasterize gives different output for multipolygons with and without internally resolved boundaries?

I was thrilled to be clued into the package fasterize, which speeds up the rasterization process in R tremendously. However, I cannot figure out why the fasterize() function outputs two different ...
0
votes
0answers
29 views

Build measure of state change

I want to be able to build a measure in ArcGIS (ArcMap). (1) I have some shapefiles of sovereign states by centuries. These are polygons with the name of the state as ID. (2) Moreover, I have a ...
0
votes
0answers
39 views

Locating observations that lies within a collection of Polygons (Python)

I'm trying to locate the observations that lie within a collection of Polygons but my current implementation takes forever, and I suspect that it is because the 'within' method needs to check all ...
0
votes
1answer
33 views

What do you call this combination of two district maps?

My real-world problem is that I want to combine state House and Senate legislative districts so that a user can pick a region (not a point) on a map that is included in both their House and Senate ...
1
vote
2answers
90 views

ST_Union in PostgreSQL and QGIS

I have a problem with understanding of the ST_Union (PostgreSQL) and the union function in QGIS. Basically, I have as an example two layers A and B that overlap. The result when using union in QGIS is ...
2
votes
1answer
126 views

Using ST_UNION to combine several polygons to one MULTIPOLYGON using PostGIS?

I have a problem with ST_UNION So, I have a several polygons DB looks like this I need UNION all off those polygons to one multipolygon and get result that looks like this I tried use ST_UNION ...
0
votes
0answers
79 views

How to remove artifacts with SQL Server GEOMETRTY::UnionAggregate()

We'd like to do an effective "real-time dissolve" on an Esri feature class with a SQL GEOMETRY shape where a parcel layer is "dissolved" into products using an attribute (ProductID) of the parcel ...
1
vote
0answers
164 views

Shapely : cascaded_union seems to return too many polygons

I'm trying to get the union of around 4,000 polygons using Shapely's cascaded_union function. The output of this function is a multipolygon in my case, which is normal since many input polygons do not ...
0
votes
0answers
24 views

Union very large layer in FGDB and only keep one polygon that is overlapping?

I'm trying to union an exceptionally large layer (45k features) of footprints with many of them largely overlapping. I'd like to union this layer but I'm having trouble due to the size of it. The end ...
2
votes
2answers
112 views

What is the proper name for the “Venn diagram” of a set of geometries?

Sometimes, you have a set of overlapping geometries, and you want to generate an output like this: Image taken from this answer. The resulting polygons have no overlaps; each region of space is ...
0
votes
0answers
9 views

MySQL group union

I want MySQL to merge many geographies together to form a single shape. A zipcode table has a row 'shape' containing a perimeter from Uncle Sam. Definition here: https://www.db-fiddle.com/f/...
1
vote
0answers
36 views

QGIS 2.18.14 valid option for union tool?

Using QGIS 2.18.14 there is no satisfying Union method. The integrated QGIS Union tool generates incorrect outputs if complex polygons (e.g. street network) are used. The SAGA Union Module does not ...
-2
votes
1answer
38 views

Filter four features from a vector shapefile to create a new layer to perform buffer, intersection and union on it, in QGIS 2.18?

From a dataset that contains points of interest defined by type of object with four different features, I am trying to distinguish the features to perform different analysis. Thought I had to filter ...
0
votes
1answer
27 views

Merging layers with preferences or ranks using ArcGIS Desktop?

I want to make a "Mosaic" or a "Compilation" of 20 shp. layers which some of them are overlap. The layers has a field named "Year" and I want the newest be on top and delete the overlap older shps ...
1
vote
0answers
141 views

Why is Union in ArcMap much faster than other approaches? [closed]

Taking the union* of these two large shapefiles file1 file2 locally using ArcMap takes appr. 10 min. Over the last few weeks, I've tried to obtain the same results using other, open-source ...
2
votes
0answers
374 views

Overlay Union Geopandas improve performance

How to speed up the "union" of two shapefiles using geopandas? I have two large shapefiles: geodataframe_left.shape = (3610, 12) (500 MB) (link) geodataframe_right.shape = (16396, 3) (200 MB) (link)...
2
votes
0answers
53 views

Seeking UNIX alternative for ArcMap Union with good performance?

I've been trying to create a union* of two shapefiles using a Unix-based approach. So far without success. My two shapefiles can be found here. The process using Union (analysis) takes ...
3
votes
4answers
185 views

Seeking PostGIS equivalent to GeoPandas union overlay?

What is the PostGIS / PostgreSQL equivalent of the GeoPandas Overlay Union operation? res_union = geopandas.overlay(df1, df2, how='union') Say I have two tables, 1 green, 1 red with each with two ...
2
votes
2answers
177 views

Combining two spatial tables in PostGIS

I have two PostGIS tables with geometries. One with number attributes and one with letter attributes. Each table has two features (rows). I would like to apply a operation on both stables so that I ...
5
votes
1answer
316 views

Only union/dissolve intersecting features to save time?

I have one table of about 300k polygons, some overlapping but most do not. I need to dissolve the overlapping ones and also keep the non-overlapping ones. I only need the geometries, no attributes. I ...
4
votes
3answers
184 views

Using postgis to flatten all polygons in table

I have a table with many polygons. The polygons all have a name and a value. I want to flatten these polygons so that each polygon border remains as border to the resulting polygons. Instead of ...
1
vote
1answer
208 views

Speed up intersection, union in PostGIS?

I have three tables: water, wetlands and parcels. I want to update parcel table with area that is covered by water or wetland (they can overlap). So I want to Merge water with wetland Dissolve and ...
0
votes
1answer
51 views

Using Union in ArcPy for ArcGIS Pro results in two fields with same name?

I just performed a union in my Python script between 2 features that both had a field attribute named "FLD_ZONE". My hope was that one of those attributes (for the second feature, I assumed) would be ...
0
votes
1answer
194 views

RuntimeError: Object: Error in executing tool when running Union

I have a list of a 2 layers (nfhl_fld_haz_features, prelim_fld_haz_features) and a feature class (master_merge) that I want to perform a union on: wkflw2_union = arcpy.Union_analysis([master_merge, ...
3
votes
0answers
154 views

Using Union tool in QGIS?

Here is my scenario: I am trying to use Union to combine the land and mangrove shapefiles in QGIS and to compute for the areas of each individual geometry. What I did: First, I cleaned them. Upon ...
1
vote
0answers
155 views

Dealing with a hole (or inner ring) at the intersection of two MultiPolygon polygons in Python Shapely

I have a problem with Shapely geometry object MultiPolygon (the exact data is shown below) in Python. I need to find a way to merge the small grid cell polygon with the larger polygon but after ...
1
vote
1answer
36 views

QGIS Union erroneously creating gaps

I'm trying to do a union between two Polygon Shapefiles, but when I do Vector > Geoprocessing Tools > Union I have the odd issue where most of it works fine, but some areas are returned in the union ...
0
votes
1answer
65 views

R sf extrapolate grid from centroids

I've got a grid/raster in R that is represented as centroids of the grid instead of polygons. I am trying to merge that with points. library(sf) nc <- st_read(system.file("shape/nc.shp", package="...
0
votes
1answer
105 views

How exactly do I use the GeoDjango Union function?

I have two models in my application: class Organization(models.Model): consortium = models.ForeignKey('Consortium') org_map = models.MultiPolygonField() class Consortium(models.Model): ...
1
vote
0answers
430 views

ArcGIS Repair geometry doesn't solve “Incomplete void poly” error

I'm working with 8 shapefiles at approximately 63 mb in size total and I am trying to use ArcGIS/arcpy's Union to combine them into one single dataset. Each time I run this, I get the error: ...
0
votes
1answer
190 views

Dissolve/merge polygons using ST_Union in CARTO

I am attempting to dissolve the boundaries between several polygons using a common attribute within a column in CARTO and the ST_Union function. In my scenario, I have created a table for all US Zip ...
0
votes
1answer
30 views

Deleting lines after manual union in ArcMap?

I have a question regarding the editing tools. I have made this selections of lines then used the "union" tool to make them into one entity but the lines that were merged together are still on my ...
1
vote
2answers
249 views

arcpy Geometry.union(Geometry) ValueError

In this script, I want to extract several polylines from one polyline. The data comes from this link : Lignes aériennes RTE au 22 décembre 2017 INF 45 kV In the flow, I merge the extracted polylines ...
0
votes
1answer
37 views

Union of Polygons with slightly shifted coordinates

I am trying to join some polygons using ST_Union but I am facing some problems due to slightly shifted coordinates of the polygons. Here's an small example of two polygons I would like to merge: The ...
1
vote
1answer
41 views

Spatial Overlay or Join with Ranking Logic?

I have two vector polygon files. One is flood zones and the other is parcels. I need to add the flood zone category to the parcel file, this is easy enough. However, some of the parcels have ...
1
vote
1answer
197 views

ArcMap Way to merge two shapefiles and take the average of their polygons that overlap?

So I have two shapefiles that show storm surge height values for two different areas. Nevertheless, they overlap for a good portion of their areas. When I merge them together, it seems that the ...
0
votes
1answer
96 views

Union from all feature classes from feature set using ListFeatureClasses

I want to use the union tool in ModelBuilder to combine ALL the features from two feature data sets from two different gdb together. I use ArcGIS 10.5.1 with an advanced license. I tried to use the ...
1
vote
2answers
59 views

Vector layers seem not to be aligned when performing 'union' in qgis

I have two files (shapefiles). A file with 50x50 meter cells. and a grid with 100 by 100 meter cells. I want to do 'union' so that I know which 4 cells of the 50x50 meter vector layer make up one cell ...
1
vote
0answers
142 views

Intersection throws com.vividsolutions.jts.geom.TopologyException: Found null DirectedEdge

When I make union of 379202 List<Polygon> rectangles rectangles and execute intersection with bounds UnaryUnionOp.union(rectangles).intersection(bounds) then I get: com.vividsolutions.jts.geom....
0
votes
1answer
554 views

Why gdf.explode() doesn't work?

I'm trying to merge 2 geodataframes and combine all entities. So I use : cloudNshadow = gpd.overlay(cloud, shadow, how='union') cloudNshadow = cloudNshadow.unary_union() But it returns me : ...