Hi all,
I’ve tried to come up with a better title, but I guess the images below can explain much better.
I wonder what could be the way to cull out points from grid not only odd/even rows/columns, but also from the multiple of rows/columns’ common divisor. Assume that the # of rows/columns are always odd numbers so the first and last will always remain after culling.
Points covered by greens are meant to be culled.
24x18.gh (3.5 KB)
Your GH file contains only a flattened list of points with no code to generate the green areas.
Not enough to work with.
I think the best solution is using And operator on one (or more) list of booleans
of course this requires a full grid 
and it becomes much easier if the grid is branched by rows or columns of points
here the original random pattern is recreated by checking the distance of each point of the new grid with each point of yours:
at this point, the easiest way I thought to cull rows and columns “simultaneously” is to apply and And operator to a given (custom) List of True/False pattern with identical tree-structure, and to the flipped matrix of that very same structure:
the combination of the two True/False pattern applied to the list can be represented by something like this,
first it goes -for instance- True/False by columns:
when you combine those two together with an And operator, if a point is False on either of the two list, it will become False, if it’s True on both of the list it will stay True
this way you can combine and overlap whatever pattern you like:
Okay… Has this forum rule been suspended? 
7. This is not a do-my-work-for-me group
It started out in one direction, then changed, but I really don’t have time to make this perfect.
