Lists (index) difference

Hi folks! I don't know if the title of this post is the correct one. I am super new on grasshopper.

I am facing this problem now.

I have 3 panels - list of index. I need the following

List A has all the index numbers.

List B has some index numbers taken from List A.

List C should the elements from List B + the elements of list A minus B.

I might not be using the correct terms. So here is an image to explain better.

Thanks

Replies to This Discussion

Permalink Reply by David Rutten on April 13, 2016 at 4:33am

A - B + B is just A as far as I can tell.

You're probably looking for Set components to do whatever you want to do though, they allow you to find duplicates, intersections, unions and differences between sets of simple data types such as integers and text.

Permalink Reply by Vicente Soler on April 13, 2016 at 4:55am

It could also be indeterminate if B is infinity.

Permalink Reply by David Rutten on April 13, 2016 at 4:58am

Or maybe a value of 18 in B removes ALL 18s from A?

Permalink Reply by Max Fabris on April 13, 2016 at 5:27am

Hi David, thanks for your quick reply. Sorry for the questions. Maybe what I need is much simpler than what I tried to explain.

See if the following image explains better what I need.

Thanks a lot!!

Attachments:

lists b.jpg, 212 KB

Permalink Reply by Michael Pryor on September 27, 2016 at 5:01pm

It exists. Look at the "sift" and "combine" components. Sift is essentially the same as dispatch with the major difference being that it keeps placeholders for each lists items that went to the other list with "null" values. Then combine component re combines the list after you have modified elements in one or both of the lists via these null place holders. I am using it quite frequently for exactly the thing you show above. You will just need to define a pattern logic to sift the list based on how you want to select things.

Permalink Reply by Michael Pryor on September 27, 2016 at 5:23pm

see here some quick examples.