8

Sorry, I can not provide an answer for QGIS 3.4, but for 3.8+, in case you have a chance to update. The tool you need for this is called join attributes by nearest, which was introduced with 3.8. For earlier versions there is a plugin called NNJoin, but this allows only to join one nearest feature, not several. I have two point layers in UTM (so join ...


4

LR will calculate distances along separate river segments. To apply it you need "long" rivers starting at multiple upstream points, ending at outlet(s). If you are capable of producing geometric network you might use script from here, to calculate distances of network nodes to outlets and apply LR later. Alternative to it is using raster approach, namely ...


2

In The influence of urban form on spatial costs, the radius used is the radius of the circle that has the same surface area than the analyzed area (accesible area of a service from an urban area with its surrounding area of non-urban land, to simulate monocentric cities). In any case, using that kind of "authalic circle" seems to me a good option.


2

The new (or modified) row is available in the trigger using the NEW record. You can directly use its geometry or any other attributes to query the 2nd table. The output of the query is then saved in the NEW record, and when done the entire record is commited. CREATE OR REPLACE FUNCTION public.tg_f() RETURNS trigger AS $BODY$ BEGIN SELECT ...


2

For sure, "closest" will return different points, in general, for great-circle (what you call haversine) and geodesic distances. For a specific example, consider the set of points {A, B} where the positions (lat, lon) are: A = (10.03°, 0°); B = (0°, 10°). The point P = (0°, 0°) is closest to B according to the great-circle distance, ...


1

Assuming your buffer layers have the same name as your line layers then you could use a make feature layer tool using the Name output from your iterator to construct a layer, this could then be connected to your euclidean distance tool as an Extent setting.


1

You can achieve this in two steps. First you need to create a raster with the distance to your line using the tool Euclidean Distance. This will create a raster from 0 to 20 (if you limit the distance to 20m). And from here you can operate this raster using the Raster Calculator that in your case would be dividing your raster by 20.


1

In R you can create a grid, please take a look at this documentation: https://www.rdocumentation.org/packages/mapplots/versions/1.5.1/topics/make.grid Please take a look at this page, that might be what you need: (images taken form the same page, attributed to the author "Huanfa Chen") https://rpubs.com/huanfaChen/grid_from_polygon I hope this helps.


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