Hgrnh!! I honestly feel for you. I hate these mysterious bugs.

I've checked that my grid code does not alter the results relative
to the non-pyd version without the grid. Also, if you didn't change
the inner loop, then the grid filtering should apply with pyd, as well.

When you went back to non-squared distances, did you change the line

if ((not no_pyd) and dist <= threshold) or (no_pyd and
dist <= threshold**2):

back to

if dist <= threshold:<br></br>
as well?

ETA: Sure, send me what you have. It's a long weekend here.

-- I'm not mad at you, just Westphalian.