How do I delete randomly a specified percentage of geometry objects?

MAXScript FAQ > Working With Scene Nodes > How do I delete randomly a specified percentage of geometry objects?

A user asked:

I'm trying to create a script that will delete a certain percentage of the objects in a scene. I want the objects to be chosen randomly. I want the script to affect only the meshes.

Answer:

Here is a possible approach:

SCRIPT

(
-- Collect the object of a certain type into an array, for example
-- this one collects all geometry objects, excluding the target objects
-- which are of Geometry superClass for pre-MAXScript historical reasons
 
candidatesArray = for o in Geometry where classof o != TargetObject collect o
 
-- Because you want to remove random objects, but a specified percentage,
-- it is a good idea to make the decision which objects will be deleted
-- BEFORE actually deleting any objects.
-- You can create a second array and fill it up with the actual
-- objects to be deleted:
 
deathRowArray = #() -- init. an empty array
thePercentage = 50.0 -- define the percentage
 
-- Calculate the number of objects to delete:
numberToDelete = (thePercentage / 100.0 * candidatesArray.count) as integer
 
-- Loop until the deathRow array is filled
-- with the desired number of objects:
while deathRowArray.count < numberToDelete do
(
  newIndex = random 1 candidatesArray.count --generate new random index
  --if not already chosen, add it to the deathrow array
  if findItem deathRowArray candidatesArray[newIndex] == 0 do
    append deathRowArray candidatesArray[newIndex]
)
delete deathRowArray --finally, delete the collected objects
)

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