Max_expected reference coherence calculation for spatial coherence

[erik40021]

Hi,
thanks a lot for publishing the code and for this interesting approach!

I am applying your scripts to calculate spatial coherence in 10x visium samples and there I stumbled across this function:

one_val = function(spots_num) { 
  a = sqrt((4*spots_num)/(6*sqrt(3)))
  oneval = (6*spots_num-12*a-6)/spots_num
  return(oneval)
}

As I understand it estimates the maximum expected coherence in a window of spots for the given number of spots assigned to the metaprogram/cluster in question.
However, it is unclear to me how the formula that is implemented here works. Could you explain the maths behind this function?

This would help me a lot!!
Thanks in advance,
Erik