Questions tagged [aggregation]
To combine data into larger units. For example a group of points to a polygon, or political subdivisions (provinces) to larger entities (country).
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questions
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0answers
18 views
Unioning PLSS Polygons
I want to union a set of Public Land Survey System (PLSS) polygons in a PostgreSQL/PostGIS layer, based on two fields, ‘sec_qtr’ and ‘qq’. A sample subset of polygons looks like this:
I want to ...
1
vote
1answer
27 views
Aggregating pixels of raster dataset using ArcMap
*I am fairly new to working with raster data in ArcMap. *
I have a raster dataset like in the picture I have uploaded, and you can assume that each individual pixel of the raster has a value which is ...
0
votes
0answers
20 views
How to add up election zone voting upto county level?
Sorry if it is a trivial question.
I am trying to add voting data from election zone up to county-level using spatial join tool, but I cannot figure out which relationship I should use. When I use ...
3
votes
2answers
76 views
Aggregating numerous polygons into one with PostGIS
I have this PostGIS query which aggregates many polygons according to a variable ("region"):
SELECT ST_AsGeoJSON((ST_Collect(polygons)),3) as geom FROM table GROUP BY region;
The ST_Collect returns ...
1
vote
1answer
53 views
QGIS 3.14 vs PostgreSQL 11.5 : same query, different result
My layer has 82431 points. Each point has an attribute var with a single value a, or b or c,...
I snap points, group by geometry and count the number depending the var attribute.
So I start with :
...
6
votes
2answers
156 views
Get all related attribute values from features in list (QGIS)
According to this question: Get Attributes from 1:n relation in QGIS as Expression to use in Atlas I try to bulid waysigns for a hiking-GIS using the QGIS Atlas. The user should be able, to choose the ...
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0answers
29 views
Aggregate Willmott and Matsuura Temperature Climate Data on Country Level
I'm looking for monthly mean temperature data on the country-level since 1900, or at least 1950, with temperature weighted according to population density.
The common database for the spatial ...
0
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0answers
30 views
Google Earth Engine Error when applying PCA on an aggregated image
I am getting this Error when applying PCA on an aggregated image using .median() method: Image.reduceRegion: Provide 'geometry' parameter when aggregating over an unbounded image.
I have applied the ...
5
votes
1answer
259 views
Counting number of features within another feature using aggregating function in field calculator of QGIS?
My data: 1 polygon layer + 1 point layer
My target: Calculate the number of points and the sum of a field within each polygon using the aggregate function in the QGIS field calculator.
I know I can ...
3
votes
1answer
111 views
Assigning parent polygon using QGIS?
I use QGIS 3.8.0 and I'm looking for tools to assign a polygon parent depending on the value. I attach the picture, where there are several polygons with different names.
I would like to get the name ...
2
votes
1answer
54 views
Generating map with polygon aggregation in PostGIS
Generate the map of federal units from the municipalities map in PostgreSQL with PostGIS.
Example below:
The table has only the geometry information and the "id".
I tried:
SELECT st_union(m.geom)
...
1
vote
1answer
73 views
Google Earth Engine, imagecollection aggregate_max (or min, or min), return null. What's the problem?
I am a little confused about this function in ee.ImageCollection:
aggregate_max(property)
Aggregates over a given property of the objects in a collection, calculating the maximum of the values ...
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0answers
242 views
Line segment overlap aggregation / analysis in Python?
I have a large sample of gps coordinates, and I would like to create a similar analytical visualization to that in Overlaying lines and aggregating their values for overlapping segments using R?
Does ...
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0answers
31 views
Reclass raster map areas smaller than specified area size
I need to reclassify raster areas smaller than 100m2 (0.01 ha) to new ones.
r.reclass. area from GRASS GIS does the job for some raster sizes, but simply stucks/doesn't work on bigger ones (54000 x ...
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votes
1answer
39 views
Calculating new raster metrics without polygonizing in R?
I have an enormous number of large rasters representing tree canopies. Every individual canopy has a unique number that is assigned to each pixel that is part of the tree. I am working with R and the ...
2
votes
4answers
458 views
Count touching and near points for every polygon (QGIS)
I have a polygon and a point layer. The polygons contains buildings, the points should be the edges of the buildings. A building is "good" as much as points are touching or in the near (buffer 0.2 ...
3
votes
0answers
211 views
Aggregate functions in QGIS using spatial intersection
I am trying to compute a virtual filed using aggregate functions in QGIS (3.6). I want to compute the average on a field in the child layer based on the spatial intersection with the parent layer. ...
2
votes
2answers
107 views
Get attributes from touching lines in network - results seems random
This question is similar to this one: Get attribute from touching line layer (QGIS) but there is a new and more komplex problem in that context I need to solve:
I have to plan drains, usually along ...
4
votes
1answer
109 views
Labeling polygons with the number of related table entries in QGIS
Using QGIS 3.6.1 I have a layer with areas and a table with entries related to the areas:
A relation is defined like this:
What I would like to achieve is to label the areas with the number of ...
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vote
2answers
161 views
Rescale raster to custom resolution using sum as the function to aggregate
I have a 0.0083 resolution population raster dataset which I would like to upscale to a 0.5 resolution raster. In particular, I would like the aggregation process to sum all the 0.0083 pixels ...
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0answers
40 views
When using Aggregate Polygons tool in ArcGIS Pro, some new shape areas and length result in zeroes?
I used the "Aggregate Polygons" tool to aggregate 265 polygons, and the tool gave me 268 new polygons, but 80 of them display a shape_area and shape_length of zero. When I try to calculate area for ...
3
votes
1answer
80 views
Count features in polygon by using aggregate (virtual field)
I have a points layer and a polygon layer. The points are placed randomly. Some are within a polygon, some are outside. I would like to write the amount of points inside each polygon as virtual field ...
0
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1answer
45 views
Trying to Count Number of Points within Specified Distance from Lines using Carto?
There were multiple points stacked on the same coordinates that I did not notice.
I am trying to count the number of points within 10km of lines (routes) so the routes can be styled according to the ...
2
votes
2answers
197 views
Calculating point layer values within polygon features in QGIS 2
There are two layers
polygon BereichBerechnung with a field "Are_Number"
points EW2017 with a field "EWjeAdr"
In QGIS with a Virtual Layer, I want to calculate the sum of the field "EWjeAdr" for ...
3
votes
1answer
142 views
Line width and labels based on blended values of features sharing same geometry in QGIS
I want to appropriate line segments that share the same geometry with a particular line width and labels based on the aggregated values of one field "GIS@BUS_5_Min".
My attribute table and polyline ...
0
votes
1answer
130 views
Aggregating or summing field by two or more criteria using QGIS?
I am using QGIS 2.18.
I'm trying to sum fields based on two criteria with filed calculator.
I have the "ID" field and the "ZONE" field (ID is secondary key, repited for other table). ZONE field has ...
3
votes
1answer
380 views
Referring to the parent layer with aggregate functions in QGIS
I'm trying to find how to refer to a field of a parent layer as a filter for an aggregate function. The instructions specify that the parent layer can be referred to with the variable @parent, but I'...
2
votes
0answers
488 views
Correct resampling method to simulate lower resolution satellite data?
I would like to simulate lower resolution satellite imagery from continuous higher resolution imagery. For example I want to use Landsat derived leaf area index data with a resolution of 30 m and ...
2
votes
2answers
187 views
tool for point aggregation and mean calculation
I have the huge number of points spread across some map.
Is it possible to calculate the mean value of a parameter in the points of a small area and make one point for the same so that the total ...
2
votes
2answers
222 views
Cartographic generalization: Dissolve “neighbour” / bordering polygon objects in QGIS
I have a polygon layer with buildings for the area of the whole city.
My question is how to dissolve/aggregate/merge only those buildings, that are "neighbours", in a sense that they share at least ...
1
vote
1answer
106 views
Joining attibutes by location + aggregation per field
I am new to QGIS.
I have a point layer (water permits) and several buffer layers (different distances from WWTPs). I can use "join attibutes by location" and find out the number of points and the ...
3
votes
2answers
74 views
Aggregating polygons with Basic level licence of ArcGIS Desktop?
I need to aggregate near-by polygons, but it has to work with a Basic ArcGIS Desktop Licence. I can't use the Aggregate tool (only Advanced) and I can't use the buffer tool, because the rounded edges ...
1
vote
1answer
232 views
Error concatenating lines in Oracle Spatial
The function SDO_AGGR_CONCAT_LINES is returning an error when concatenating lines from a table with simple line geometries (SDO_GTYPE - 2002):
ORA-29400: erro do cartridge de dados
ORA-06502: PL/...
0
votes
1answer
84 views
Aggregate and split layer by location into multiple layer in ArcMap? [duplicate]
I'm pretty new to GIS, but hope I'm moving in the right direction. I have a layer of the county map of LA, which is divided into communities and a layer of the building coverage of the county. The ...
2
votes
1answer
201 views
Creating an aggregate function filtered by entry value
Can anyone help me parse an aggregate function for Qgis 2.18 which sums the values of one field, for all entries which match a value of the entry in question.
So, for example if I have a simple ...
2
votes
1answer
119 views
Aggregating/Averaging NDVI across pixels. Arithmetic mean seems bad choice
I need to compute an aggregate index for vegetation density in certain (large) shapes, to assess desertification. I have NDVI data at a high spatial resolution (~100 NDVI-pixels per aggregation shape, ...
3
votes
1answer
203 views
How to calculate the number of polygons along a line segment in QGIS
The image below is a representation of a digitised urban area derived from Google Satellite and OSM. The black lines between nodes are street segments and the irregular polygons are households.
I ...
3
votes
1answer
156 views
Aggregating strings in QGIS
My inputs are in this way :
col1 col2 col3
1 a c
1 b c
2 c c
2 d b
2 e z
And I would like to obtain :
col1 col2
1 a, b
2 c, d, e
I ...
2
votes
1answer
118 views
Working with Sentinel-2 data and aggrigation in R
So I was wandering if there is a way to simplify a couple of Sentinel's rasters so I can apply raster analysis on them. Problem is that whenever I try to aggregate the data my RAM, CPU and storage ...
4
votes
1answer
117 views
Visualize challenge: show origin of aggregated minimum r.series job
Using r.series with the aggregate minimum option I'm merging multiple viewshed results to visualize how much vertical space a development area has for new buildings. Meaning that a part of the height ...
2
votes
1answer
124 views
Expression Builder in QGIS in editing Attribute Table
I am working with a simple attribute table that has 4 columns;
'Xcoord'
'Ycoord'
'id'
'id2'
'id2' is a new field that i added to the attribute table.
'id' is a field showing land use classes with ...
5
votes
1answer
2k views
Aggregating raster using GDAL?
I have a GeoTIFF which is at 30m resolution. I need to downsample it to 250m resolution (using some aggregating function such as mean, mode, sum). My stack is python (rasterio and GDAL bindings)
I ...
0
votes
0answers
301 views
Is there a way to retrieve shapefile attribute table information for a given coordinate in R?
Does anyone have an idea how could one get information out of shapefile attribute table (class SpatialPolygonsDataFrame in R), in my case data from column that contains species names, based on a list ...
2
votes
1answer
139 views
Aggregate polygons in edit session using ArcObjects and c#
I want to aggregate some polygons in edit session using ArcObjects and c# language. In other words, my purpose is to use methaheuristic algorithms for polygon aggregation. So, I want to aggregate some ...
12
votes
2answers
305 views
Aggregate Lines Based on Distance between Segments
I have a VectorTile basemap that I am optimizing, (working on reducing the size of individual tiles), the major chunk of tile size is road data (geometry and attributes). I am working on simplifying ...
1
vote
1answer
304 views
Aggregate by date-time and compute a centroid as an output?
(I would prefer using R if possible)
I have a table with coordinates (in latitude, longitude), time information (YYYY-mm-dd HH:MM:SS) and ID information (example provided). I sometimes have multiple ...
0
votes
1answer
37 views
Filtering out class from high resolution map in lower resolution map?
I have a soil sealing fraction map (SSF) with a resolution of 30 meters and a high resolution land cover map (HRLC) with a resolution of 5 meters.
I would like to use the HRLC map to filter some ...
1
vote
1answer
1k views
R spatial aggregate, IDs out of order
HUC12_intersects is a SpatialPolygonsDataFrame object with over 5000 polygons
library(rgdal)
library(sp)
library(rgeos)
library(raster)
library(maptools)
HUC12_intersects@data
AREA_ACR_1 GEOL_CODE ...
-1
votes
2answers
827 views
Aggregation of MODIS 16 days data to annual data set
Is there a way to calculate mean annual NDVI and mean annual EVI from the time series MODIS images (2000 - 2016). I have gridded data downloaded to the local drive. Planning to use R for this work.
3
votes
1answer
198 views
Change raster cell size while keeping attributes
I have a raster with a cell size of 1 and I want to increase the cell size to 5 so I use the Aggregate() function in ArcMap 10.4.
The problem I'm seeing is that after processing I lose the desired ...
