How to Randomly replace Blocks?

Grasshopper
, , , ,
1

So here is my problem:
I have a 290 blocks (facade panels) named Block A already present at their final positions in the model.

Now I would like to replace a certain percentage or fixed number of them with other Blocks called B and C (E.g. Block A: 30%, Block B 50%, Block C20%)

The selection should be randomized, ideally with a seed number so I would be able to generate different solutions easily.

I searched the archive, but I did not find anything there…

Can someone give me a hand?

Thanks in Advance

Andreas

image
image1920×1482 213 KB

2

Are you working with Rhino 8?

3

yes I do :wink:

4

Get the total number of block planes.

In Grasshopper, duplicate every block as many times as you have planes.

Random reduce in each set of blocks

place the blocks
…

If you can get it to work, post your files.

1 Like
5

Here is a simple python script to do this for you.

import rhinoscriptsyntax as rs
import random

def RunScript():
    # Get the objects
    instances=rs.GetObjects("Select blocks to replace", rs.filter.instance, preselect=True)
    if not instances: return
    
    block_A = rs.GetObject("Select first replacement block", rs.filter.instance)
    if not block_A: return
    
    block_B = rs.GetObject("Select second replacement block", rs.filter.instance)
    if not block_B: return
    
    # Turn off redraw to speed up the process a lot
    rs.EnableRedraw(False)
    # Find block names
    block_A_name = rs.BlockInstanceName(block_A)
    block_B_name = rs.BlockInstanceName(block_B)
    
    # Define variables for percentage of each replacement (0.2 = 20%)
    var_A = 0.2
    var_B = 0.3
    
    # Check random number against variables 
    for instance in instances:
        rnd = random.random()
        
        if rnd < var_A:
            xform = rs.BlockInstanceXform(instance)
            rs.InsertBlock2(block_A_name, xform)
            rs.DeleteObject(instance)
        
        elif rnd > 1-var_B:
            xform = rs.BlockInstanceXform(instance)
            rs.InsertBlock2(block_B_name, xform)
            rs.DeleteObject(instance)
    
    # Turn on redraw again
    rs.EnableRedraw(True)

RunScript()

And the test file I used:
Block replace test file.3dm (569.3 KB)

image
image1493×634 69.1 KB

1 Like
6

Thank you so much both Martin and Holo,

You guys rock!

I really wish I could offer something in return…

Do you think something like this might work?

Thanks again

Andreas

1 Like
7

Using the random component to select one two or 3 options can be done this way also:

image
image1920×1202 68.6 KB

2 Likes
8

Thanks Scott,

I think I have to hone my GH skills, I don´t understand the icons (yet)
My knowledge is very basic.

Back to school I supose :wink:

1 Like
9

Run random into a greater then component to see if the random number was higher or lower than .5 or whatever the percentage of one option vs another is. That will create a true/false list that can be used in a pattern component that switches between the two options above.

1 Like
10

than

:zipper_mouth_face:

1 Like
11

My pleasure and thank you for wanting to buy us a coffee :smiley:
I liked the idea and made an account: https://buymeacoffee.com/jorgholo
So fun!

12

enjoy :wink:

1 Like
13

Wohoo! You made my day :smiley:
image