Calculating on which surface is a curve which not

Hi there!

I guess its kind of simple but I do not know how Grasshopper can tell me on which surface there is a curve and which not. My surfaces are actually plots and the curves houses and I want to know on which plots there are no houses. Would be great if somebody could help me out!

Thank you so much!

Post the file.
It is simple indeed.

it is too big…

this is a snapshot of a part of it!

Extract a fragment of it.
We are keen to help you but we don’t want to build the file to demonstrate how it works.

housesandplots.3dm (9.7 MB) (42.7 KB)

Where is this file coming from?
Some curves are not recognised, not able to explode. It requires manually re-drawing them.
Just figured out: some polylines are exploded but grouped, you will need to join them manually in order to be recognised.

Here is your answer:

There are some errors due to the map drafting quality. You’d need to spend some time making sure both houses and plots are outputting clean and closed curves.

That is amazing thank you so much!!