Parametric list, element by element

Hello everyone,

I’m quite new to grashopper hence I am not sure if my idea is feasible.

I am working on rather complex geometry which involves a step where a list of numerical values is computed for further use. Important - the number of values in the data series is not constant and in principle can vary.

What I would like to be able to do is manipulate selected data in the list and be able to do it in a dynamic manner to preview how the final geometry changes. Below I show an example:

Point no 2 and no 4 from the list need to be changed so I multiply them by a certain factor.

The reason for this is that the data series is based on a mathematical expression which in some cases gives non physical results that need to be corrected by hand.

Is there a plugin or perhaps build in component which would allow me to do this?


if you want modify a value you can select item by index ,change it than replace it
that what i understand from your image

Using gene pool could be a clean solution


This will not work for me because the index of the item to replace is not constant and it could be 2 or 3 items that I want to change not just one. also the list may at one time contain 10 elements and in some other case 20


Gene pool does not accept input data. The “initial data” in my screenshot is obtained from previous manipulations on existing geometry. I would like to be able to inspect it, and modify before feeding into the next component.

What I would like to do is something in the manner shown in this old scrip I found by googling.

So to have a series of sliders from 0 to say 2, each of which remaps a single entity in my list. The problem here is that the list count is not constant …
tube_Graft_Bang.ghx (262.9 KB)

use replace items; you already know the index so it’s easy to replace them


Thnaks , that could work but I came up with a “more automatic” solution using bumblebee and excel.

Perhaps someone can use in the future …

param_list_test.7z (36.0 KB)

Simple that’s what I meant. There are some scripts around which updates the gene pool so you can do it easily with various list sizes.
Edit: should repliy to @kma.s

1 Like

Wow Tim this is exactly what I was looking for.

Thanks a lot!

But he wanted a Multiplier, not replacing with a new value…