# More fun with arrays

Here’s a recent array question from the mailing list: How do you build an array that looks like this?

`[0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, ...] ?`

I didn’t check the other answers yet, because that would be cheating 😉

When I look at that array, I see a repeating sequence of four integers, so that naturally suggests doing something with the Modulo node. Using the If node is nice for clarity, but I could simply take the Boolean output of the comparison node.

# Simple example of a parametric point cloud

Here’s a simple parametric point cloud that shows the two techniques for using arrays instead of Repeats that I blogged about earlier:

I used this set of parametric equations to get a cylinder point cloud:

x = sin(u)
y = cos(u)
z = v

where

0 <= u <= 2*PI
-2 <= v <= 2

For this exercise, I simply used Build Interpolated Array to build arrays of U and V values, but I probably should use something like the XYZ_Grid_Generator technique described by Daniel Brassard on si-community. Here’s a version of the ICE tree with some Show Values. I use the Modulo technique to build an array of the XY values for all points in the cloud. Then I use the Divide by Scalar technique (the integer result is truncated) to build an array of the Z values. Finally, I add XY vectors to the Z vectors to get the final point positions. 