Boolean pattern generation

Hi folks!

I've been working with numerical series to sort points on surfaces and make "kind of" complex (for me) pattern behaviour. But I got to a point wher I want something to happen and can't find the way.

I have a loooong list of ordered elements from wich i would like to subtract a random number of elements. And here comes the problem.

I could "select" instead of remove if it weren't for the random generator that generates a nice list of random elemnts BUT sometimes it generates several times the same integer, so no use as it would make instances of the same element.

The cull Nth should work if it wasn't for it not accepting a list of integers.

The Cull Boolean Pattern should be the option if I knew How to generate a random boolean pattern with a determined by me number of elements.

Any help would be kindly appreciated.