Properties can be assigned to elements but not to groups. Is there a work-around available?

[Nikola Aleksic]

I'd like to use schedules to sum-up some areas of multiple items (walls, windows, zones, doesn’t matter really), but then I'd like to make the resulting sum of those areas into a custom Property that I could then use to interact with other properties (adding, subtracting, multiplying, calculating ratios, etc.) using Property Manager and Expressions.

Basically, how do I make a custom Property that relates to multiple objects, not just one? Or can I pick-up a sum from a schedule and make that resulting value into a Property?

[poco2013]

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@Nikola Aleksic wrote:

Basically, how do I make a custom Property that relates to multiple objects, not just one? Or can I pick-up a sum from a schedule and make that resulting value into a Property?

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Properties relate only to the element to which they are attached. Even Expressions can only use the properties of the element to which they are attached. There is no workaround at this time.

if you are just interested in summing quantities of similar elements, the schedule sum option is a;ways the best option.

For multiple objects which may be dis-similar, you can use a Python Script which can access most  element types and any custom Property plus many built in Properties. Also via a short related AddOn -- any quantity. The downside is that Python scripts are not automatic but must be manually initiated.  Do you have specific requirements?  -- An example??

[Nikola Aleksic]

I was afraid that “single element” limitation in Expressions is hard-coded. That’s why I’m interested in finding a way to refer to a single schedule value like sum of areas for walls, zones, windows, etc. and play with that value. Can I extract any kind of value from a schedule and then turn it into a Property?

Python Script is currently well beyond my abilities I’m afraid and I’m looking for an “in-house-solution”, no add-ons, plugins, etc.

Also, my question was intentionally very broad as I’m interested in developing a good method that I could use on different tasks. For instance:

• Calculating ratio between total wall surface area and total glazing area. Not item by item ratio, but ratio of the total areas in the project. I can have any area listed in the schedule for both walls and then for glazing, but I can’t make Archicad have those two sum values interact in any way.
• Calculating ratio between Land Area and Building Footprint. I need two different zones to interact with one another and work that into a Property/Expression.
• I’ve got other ideas, but all of them fall into the same category of problems – make multiple items grouped into one Property value.

Maybe some GDL scripting might help? I have no idea on where even to begin such a task, I’ve got no experience in GDL scripting.

[poco2013]

The short answer to your three points is that they are not possible presently. But that is exactly why Graphisoft introduced Python and previously the C++ API. I do not recommend the C++ API as it is very complicated and poorly documented.

Any of your three points are just a minor short Python script of which many here have implemented in the past.  Graphisoft has a number of videos and articles on the use of Python in its program.

However, they do not teach the Python language and I do not know of any CAD program or CAD company  that will do that. But, there are a huge number of instructional videos on YouTube which are more than adequate to get you started.

As to GDL, I expect it can also accomplish the above -- don't know-- but I think you will find it as complicated.

Final Point, if you are completely opposed to any programing, you should just export your schedules to Excel, as this feature is built into Archicad. Do your calculations there and then import or copy/paste back into Archicad.

[Nikola Aleksic]

Thank you for your response Gerry, I appreciate you taking the time to break it down thoroughly. 

I guess I'll have to dive into Python to get these things to work, if only to implement some of the already developed scripts for tasks I had in mind.

Cheers