Picking the unit the most closely matching a condition?

[Smiddle]

Is this possible? I mean, for example, if I want to pick the unit that the most closely matches being 300µ away from another unit.

 

[Livirus]

function GetBestUnit takes group g returns unit
     local unit bestUnit = FirstOfGroup(g) //Doing this to have a unit to compare with.
     local unit u = null
     loop
          set u = FirstOfGroup(g)
          exitwhen u == null
          if SomeValueOf(u) > SomeValueOf(bestUnit) then
               set u = bestUnit
          endif
          call GroupRemoveUnit(g, u)
     endloop
     
     set u = null
     return bestUnit
endfunction

 

[Smiddle]

Thanks, but I'm kinda new to jass, could you explain what I should change?