Random with percentage probabilities for different results

[Christoph_H]

I have problems for the following configuration:
I tried to use an If Loop in the wrangler to add certain percentage probabilities.
I failed, however.

In this case:
a 20 percent probability that he does not select a point.

a 35 percent probability that he selects 2 points.

a 45% probability that he selects 4 points.

The whole thing would have to be subject to a random function with seed.
So far I have the impression that I would have to combine several random functions.
I have no idea how to do this. I also searched the Internet, but found nothing that would have helped me.

Thanks again for your help.

[kiryha]

I took the first brute force idea from this topic and implement it with VEX. Connect Attribute wrangle node to a geometry and check @show attribute in Geometry Spreadsheet:

float rand = rint(rand(@ptnum)*10);
int porbMap[] = {0,0,2,2,2,4,4,4,4,4};
int randMapped = porbMap[rand];
s@show = sprintf('%s', randMapped);

the probMap is an array where you define your conditions. I reduce array size from 100 to 10, so instead of  20 zeros for 20% probability of selecting zero points, you need to enter only 2 (30% probability to select 2 points and 50% probability to select 4 points).
Its awful algorithm and I am not 100% sure If it's working correctly. Certainly, there should be a more elegant solution!

Edited April 17, 2018 by kiryha

[Jesper Rahlff]

//pointwrangle

float randnum = rand(seed+45,65); //gives value from 0-1,

if (randnum <= 0.2)

{

dont select a point

}

else if (randnum > 0.2 || <= 0.55)

{

select 2 points

}

else if( randnum >0.55)

{

select 4 points

}

Edited April 17, 2018 by Jesper Rahlff

[kiryha]

Hi, Jesper! Nice setup!
How does this command work?

rand(@ptnum +45,65)

I did not find three arguments example in docs.
Cheers!

[Jesper Rahlff]

35 minutes ago, kiryha said:

Hi, Jesper! Nice setup!
How does this command work?

rand(@ptnum +45,65)

I did not find three arguments example in docs.
Cheers!

actually it is just the regular rand() function with one argument. I just added to that one value argument. so rand(@ptnum + 45.65 + @seed), all turn into one value. (I realize in my previous post I used komma , instead of dot to declare the decimal. its an old European habbit and is wrong. the number should be 45.65) 

[Christoph_H]

thank you both