topic Re: Selecting within a selection in ArcGIS CityEngine Questions

Selecting within a selection

MonicaClayton — Wed, 18 Sep 2024 16:05:01 GMT

I have a file with land use and building footprints. I have gotten to the point in python of selecting all the land use shps from the object attributes. In this picture:

I have written code that has selected everything tagged as residential in the object attributes.

def selectByAttribute(attr, value): shapes = getObjectsFrom(ce.scene) selection = [] for s in shapes: attrvalue = ce.getAttribute(s, attr) if attrvalue == value: selection.append(s) ce.setSelection(selection) if __name__ == '__main__': selectByAttribute("landuse","residential") pass

My question then becomes, how do I select the footprints within those already selected polygons, and nothing else? This is where I have gotten stuck.

Please help? And help me like I have no coding knowledge what so ever. I have an art degree, and the above took me almost 2 days to figure out.

Thanks in advance!!!!

Monica

Edit: Essentially, I would like to "Select by Location" like I would in ArcPRO. Which, would be a nice feature to have in general.

Re: Selecting within a selection

desert — Thu, 19 Sep 2024 03:39:51 GMT

I have referred to the link below.

getObjectsFrom

change

shapes = getObjectsFrom(ce.scene)

shapes = getObjectsFrom(ce.selection, ce.isShape)

I hope this helps.

Re: Selecting within a selection

MonicaClayton — Tue, 24 Sep 2024 15:57:32 GMT

I did, and it gave me the same results. I want to select the footprints that are within the already selected land use polygons. Like my edit, a "Select by Location" option and the location being within my already selected polygons. Is this possible? There isn't any specific or differentiating attribute on the footprints that I can use to pick them out, the only thing they all have in common is the fact they are within a polygon tagged as "landuse, residential".

Thank you for the help!!

Re: Selecting within a selection

JonasObertuefer — Tue, 24 Sep 2024 16:09:21 GMT

Hi @MonicaClayton,

There is way to do this in CityEngine although it is a rather complex workflow:

Asumming you have the landuse and footprint shapes in a different shape layer

Select all landuse shapes
Apply & Generate the following CGA on them:
attr landuse = "residential" Lot --> t(0,-5,0) extrude(10) label(landuse) color(1,0,0.5)
Connect the object attribute to the landuse attribute in the Inspector, if they are not automatically connected
Select all footprints and assign&generate the following CGA onto them:
Lot --> contextCheck contextCheck --> case inside(inter, "residential") : color(1,0,1) report("landuse", "residential") extrude(15) // add more cases for all usages else: extrude(15)
Add a new python file to the Scripts folder of the project
from scripting import * # Get a CityEngine instance ce = CE() # Called for each shape after generation. def finishModel(exportContextOID, shapeOID, modelOID): ctx = ScriptExportModelSettings(exportContextOID) shape = Shape(shapeOID) model = Model(modelOID) reports = model.getReports() if 'landuse' in reports: ce.setAttribute(shape, "landuse", reports['landuse'][0])
With the footprints still selected go to File -> Export -> Script Based Export (Python). Select the previously created python script and click on Finish
All footprints inside a landuse shape will have a new landuse object attribute with the value of their respective surrounding landuse shape.
Select them using your python script from above

I hope this is what you want to achieve. Let me know if you have any questions!

Cheers
Jonas

Re: Selecting within a selection

JonasObertuefer — Wed, 25 Sep 2024 09:11:19 GMT

To follow up on this, I recorded a quick video to showcase the workflow:

(view in My Videos)

Additional resources: