Two lists with different index. Selecting "negative" items basing on the item of second list

I have a simple question but the solution maybe will not to be too easy.

What we have to do if we have two lists of elements (surfaces/points…) with different index and we have to select, for example surfaces from first list other than the surfaces in the first list…

…The second list was created from the first but with some modifications, (for example: by used "random reduce, attractor…), so the index of items of the second list is different to index of items of the first list, but we want to select some elements from the first list but not these elements which we receive with the second list.

Maybe I described it not very clearly, I add picture.

Any help would be much appreciated,
(Sorry for my English).

Ask (201.4 KB)

Then it’s not a simple question.

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Ask (202.3 KB)


wow! I would never have come up with such an idea.
And how fast You did it!

Since I have learning the grasshopper, I saw many of many of Your post and solution on this forum.
For me it is a great day that I received a solution from HS_Kim himself! You are the legend of this forum and You are One of the grasshopper jedi masters!

Thank You very much HS_Kim! :slight_smile: (195.7 KB)

simple way…


I saw that you also often help in this forum.
You are also one of the Jedi in this forum. It is an honor for me to receive an answer from you.

Thanks :slight_smile:

…there are also some sith here…
see @PeterFotiadis :rofl: … you might find yourself pulled into the dark side!

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yes, I saw. The Siths are with us since the old grasshopper forum.
The dark side is also strong.
In @PeterFotiadis 's posts I see that he often use dark power (C#), so I’m not in any danger going to the dark side :smiley:

The only Side is the Dark Side (and there’s free cookies and cigars as well). Switch camp ASAP.

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