qgisvector-layer
I have a vector point layer with an attribute Customer with boolean values true and false. I want to aggregate this data by polygons, such that for a given polygon, it shows that Customer is XX% true and YY% false. I can't achieve this with join attributes by location (summary); I can only get Customer_COUNT from this.
Attached an example for reference — I basically want to get the % blue and green points within a polygon.
@Dano rightly raises some issues that are best addressed in a full reply.
One difficulty, already noted by @Celenius, is that a join between B and A (in either direction) duplicates all the fields; it can be onerous to correct this. I have suggested in comments that the obvious easy way (export to a spreadsheet) raises questions of data integrity. Another difficulty, already addressed by Celenius' proposal, concerns solving this problem when no combination of attributes can serve as a key for both A and B, because that precludes a database join. The spatial join gets around that problem.
What, then, is a good solution? One approach uses A to identify the corresponding records of B containing the desired data. Depending on assumptions about the configurations of the polygons--whether they overlap, whether some can contain others, etc--this can be carried out in various ways: using one layer to select objects in the other, or via joins. The point here is that all we want to do at this stage is select the subset of B corresponding to A.
Having achieved that selection, export the selection and let it replace A. Done.
This solution assumes that all fields in B are intended to replace their counterparts in A. If not, then it really is necessary to perform a 1-1 join of B (source) to A (destination). The join based on identifiers is best, but making a join on polygon identity (Celenius) works fine if ids are not available and there's no chance corresponding polygon shapes in A and B might differ, however slightly. (This is a subtle point, and the potential cause of insidious errors, because previous edits in B to polygons that don't correspond to A could still invisibly modify the other polygons in B if the GIS is "snapping" or "maintaining topology" or otherwise automatically making global changes during local edits.)
At this juncture, there are two copies of every field: if [Foo] is a common field to A and B, then the join contains A.[Foo] and B.[Foo]. Using a field calculation, copy B.[Foo] into A.[Foo]. Repeat for all needed fields. After this is done, remove the join.
Although this procedure can be a little onerous when many fields are involved, its merits include
Some of the guiding principles involved in this suggestion are
One might object that in many cases there are faster and easier ways to reach the same result. Yes, there can be, and they can be effective and usually they work when performed with care. But solutions that risk the data are difficult to recommend and defend as general-purpose answers. They are best employed in one-off situations with small datasets where corruption in the data should rapidly become obvious and the consequences of any such mistakes are immaterial.
It is now part of the standard options in QGIS 3.0 to join to more more than located feature. Many thanks to the developers that added this feature in the new release.
In the French version, the options under Joindre les attributs par localisation:
-Type de jointure
-Créez une entité distincte pour chaque entité située
Best Answer
You can use field calculator with
overlay_contains()(or eventuallyoverlay_intersects()depending on your needs) expression on your polygons for this. To get the count for each category simply set a filter to your needs, for example:respectively for the other category
Then calculate the percentage from these. So all in one:
Just replace
pointswith the name of your points layer and"cat"=1with your field containing the category and the desired value of this category.