[NTG-context] How can I compare picture variables in metapost?

Hi all, I want to draw some paths that won't intersect with each other in metapost. Those paths are generated "randomly," e.g., draw 100 circles without any intersections. I use a very stupid way like: ============================================= % randomseed:= day + time*epsilon ; save minL ; numeric minL ; minL = infinity ; z[0] = origin; for i=1 upto 99 : z[i] = (uniformdeviate 1 , uniformdeviate 1 ) ; for j=0 upto i-1 : if abs(z[i]-z[j])