8

What you are actually trying to do is a kind of Location Allocation analysis. The need for a pharmacy is determined by two things: The amount of people living in an area (amount of buildings is proxy) The distance (either Euclidean or drive time) You could use the freeware of Utrecht University; flowmap for this purpose. It is a bit 'clunky' though. Their ...


4

There is a way that could be a little quicker as it uses a faster method to query the data. Right click on the layer Select "Query" Enter area > 10000 The layer will be filtered to only show that data Right click on the layer Click "Save As..." Save the filtered layer to a new file. Remove the query from the main layer using steps 1) and 2) This uses ...


4

If you want to calculate acres in QGIS, open the field calculator and and use the following code: $area / 43560


3

There is no builtin function in QGIS field calculator that can do your task, but luckily you can create custom function in QGIS using Function Editor in field calculator, please follow the steps below Open your shapefile in QGIS. Open Attribute Table and click field calculator. Please check the box saying Update existing field and select your desired field. ...


3

I like the expression you've put together - probably no solution in QGIS 1.8, but in QGIS 1.9-dev there's a floor() rounding function which rounds down. For D°M'S'': (CASE WHEN $x < 0 THEN '-' ELSE '' END) || floor (abs($x)) || '° ' || floor(((abs($x)) - floor (abs($x))) * 60) ||'\'' || substr( (tostring((((abs($x)) - floor (abs($x))) * 60) - floor(((abs(...


2

Select all areas bigger than 10,000 m2. Either: Open the attribute table of your polygon layer, and click on the 'area' attribute column (or 'acres' or whatever you used to name it when you calculated area) to sort by area. You can then select all the rows from the 10k m2 point on down, OR - Open the attribute table and click "advanced search". In the next ...


2

You could first dissolve the layer with the overlapping polygons and then run intersect of the dissolved layer and the other layer. Then you can simply compare the area values.


2

I'd think you're using the Boolean XOr operator. Probably that expression needs to be narrow as follows: SquareRoot (((1+"NDVI.img")/(1-"NDVI.img"))*"NDVI.img")


2

This should work: CASE WHEN ("Apple" = 2) + ("Banana" = 2) + ("Orange" = 2) + ("Pear" = 2) >= 2 THEN 'green' ELSE 'red' END


1

While waiting I have done it using python: import os path=os.path.dirname ("[% "FILEPATH" %]") os.startfile (path) Maybe someone will use it... Thanks for your help!


1

This can be done, but doesn't need Raster Calculator. You could sum individual visibility rasters, but it isn't necessary as there's an easier way. You can use the QGIS Plugin Advanced Viewshed Analysis which has a cumulative option. There are other viewshed algorithms (SAGA and GRASS) which might allow this too, but from memory, the plugin is best for this ...


1

You may run the following code from the Python Console, remembering to preliminary edit the name of the fields of interest (see the comments in the code below): from qgis.core import * layer = iface.activeLayer() field = 'test' # replace this with the name of your starting field newfield = 'result' # replace this with the name of your new field layer....


1

The Con statement (conditional) is similiar to an IF ELSE statement and can be used with the raster calculator. I use it to add rasters together that have null values by converting the nulls to zeros. Con(isNull("raster_layer"), 0, "raster_layer") Esri documentation: http://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/conditional-...


1

Thanks for all the comments. I finally solved the problem, it was much simpler than I´d imagined. Effectively, the CellStatistics tool was the answer, but the result I was obtaining was a raster that didn´t comprise the total area of all my rasters. Once I added the MAX extension, it worked! Here I leave the code, in case is useful for someone dealing with a ...


1

Those instructions seem perfectly valid for the Raster Calculator in QGIS 3.0. Output file settings are in the upper-right corner of the Raster Calculator window. Enter the filepath and name for your new raster where it says "Output layer."


1

If I understood correctly (you want to transfer population layer values to mobile signal raster only where its value is 1 ?) “mobilesignal@1” * “population@1" should work. Then you can use Raster > Conversion > Translate if you want to replace 0s with no data / null.


1

The general process you've outlined is correct, but the order doesn't appear to be. You should subtract the newer DEM from the previous DEM starting from the oldest set. If the volume is larger over time, it is possible that the images are not taken at the minimum snow depth for the year. If a glacier is thought to be receding, but the newest DEM was ...


1

The modulo operator can be used to do truncation, but the resulting expression would be very ugly. It is prettier to use string substitution, but unfortunately QGIS doesn't expose any strpos or similar functions. Use regexp_replace($x, '\\..*', '') to get the whole part and regexp_replace($x, '^[0-9]*\\.', '') to get the decimal part. Use toreal instead of ...


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