expression properties from multiple elements

Marko Zeko — Tue, 24 Jun 2025 17:49:59 GMT

Hi all,

I would like to calculate percentage of plot development.

So that is sum of areas of all building divided with area of building site area.

I created three properties one is

(1) area of building,

(2) area of building site

(3) Kig (percentage of lot development).

So now Kig should be sum of building areas (in my example two of them) divided with building area.

I tried to merge items in schedule so those properties are summed up.

Prop (1) results with 0 when building site is asked for answer, while (2) results with 0 when buildings are asked for answer. Had to create expression with IF for (3) so I can get 0 as a result when buildings are asked for Kig. Otherwise I get error - value cannot be divided with 0.

So I wanted all those to be summed up.

Is it possible to get sum of the same property throughout different elements of the same type?

Another strategy was to use project info for input of plot area and than Kig is defined as "building area" / "project info plot area". This worked but plot area should be input manually. Is there possibility for project info to extract that info from property automatically?

Thank you

All three are associated with all three zones.

Operating system used: Windows

Re: expression properties from multiple elements

Laszlo Nagy — Wed, 25 Jun 2025 09:57:33 GMT

Yes, unfortunately, Properties can only work with data from the same element. So it is not possible for the Property of an element to somehow get data about another element.

I remember a long time ago, when I was trying to summarize areas of Zones, I had to modify the GDL Script of Zone Stamps so they wrote data about themselves into a TEXT file, then read all that data back from the Text file and added up all the Zone areas and that is how I could get the total Zone area and display it in my Project. But that is something you can do only with GDL-based element types.

You goal may be possible to achieve using Python, but I am not sure, I am not a programmer so someone familiar with Python should be able to answer whether it is possible or not.

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expression properties from multiple elements

Re: expression properties from multiple elements