FastLED Define Multiple Random Arrays

I'm fully expecting a bit of flame for this, but as I'm under a time crunch to see if I can pull off my last minute idea...gotta happen. I'm hoping someone will take pity on me an point me to a good example. To preface this, my experience on Arduino is measured in hours (literally... I got a Nano and the string I'm working with less than 24 hours ago), and to make it more fun I haven't done in real coding in better than 15 years (and never worked in c++). I've spent several hours cramming through any examples in FastLED I can find, was able to get something of a hello world working and get some idea of basic light controls. Where I'm struggling is creating arrays of pixels using a random selection, then being able to randomly active some pixels within a given array. Maybe a straight description of what I'm trying to achieve will help as I'm not having much luck in web searches on this one.

Using a 50 pixel ws2811 string:

  • Select random array of 25 (or maybe 30) pixels, light them solid
  • Out of remaining pixels, select 10 at random, fade from off to full bright white then back down to off
  • When above selection of 10 is fading back down, start a new selection of 10 going back up
  • Repeat loop
  • Optional, after x time start entire process again selecting new array for solid

From my crash course so far, I have a basic idea of how I can light the solid array, and fade the other array in and out, but where I'm struggling to find any example is how to randomly create the array of X pixels, then select 10 at random from the remaining pixels not part of that array, and how to start a new set fading in as the others fade out.

It would be simplest NOT to create multiple arrays. Easier to create a single CRGB array for the 50 pixels. Then, you'd set the color values for the different sections of that array per your display plan. Then, call FastLED.show() to update them all at once.