hello alex, i have an hsv to rgb patch for data structures if you want...
but for 0 to 255 rgb values, the math is simple, just divide this number by 9/255 and discard the fractional part, then multiply by the position and sum all (it gives a number from 0 to 999)
so, if you have 255 for red, 100 for green and 50 for blue
255*9/255 = 9
red position is times 100, so 900
100*9/255 = 3.529...
green position is times 10, so 30
50*9/255 = 1.764...
blue position is times 1, so 1
the number is then 931
unfortunately, data structure colors doesn't have so much resolution, so this color isn't really the same as 255 100 50, but, is what we can achieve...
(i don't remember if the order is red green blue for data structures and don't have pd right now to test, but if it was wrong, just change the positions, the math is ok kk)