relative align a object set

thanks garp for posting the simple and beautiful solution.

(
    rollout rltAlignSelToObj "Align Sel. to Object"
    (
        pickButton pb "pick object to align to"

        on pb picked obj do (
            if (n = selection.count) != 0 do (
                local pos = [0, 0, 0]
                for o in selection do pos += o.center
                move selection (obj.center - pos / n)
            )
            destroyDialog rltAlignSelToObj
        )
    )
    createDialog rltAlignSelToObj
)

Yes,that's right.
You can place three spinners in the rollout and control the scrolling through the weight alignment.
In my sample it shouuld be:
mypoint.position = [spn1*(minx + maxx), spn2*(miny + maxy),spn3*(minz+maxz)] , where
spn1,2,3 are the spinners x,y,z weight parameters: (0.01 ... 1.0) or to overweigh, the values may be >1.0.
values of 0.5 correspond with the x,y,z middle.

yep. that is mathematically right. but i was thinking kind of weighted automatic average .lets say you have four object at (-5,0,0) and one box at (5,0,0)position.
the group center is at (0,0,0)but the average center will be at
((-5)*4+5)/(4+1)=(-3,0,0)

:-) there must be simple term like for this .something like center of mass.

Hi , sorry for the late response.
You need to loop through all selected objects to find selection min x, max x,min y, max y and min z.
It will look something like:
global minxarray=#(),maxxarray=#(),\
minyarray=#(), maxyarray=#(), minzarray=#()
if selection.count != 0 do
(
For i = 1 to selection.count do
(
insertitem Selection[i].min.x minxarray (minxarray.count+1)
Insertitem Selection[i].max.x maxxarray (maxxarray.count+1)
Insertitem Selection[i].min.y minyarray
(minyarray.count+1)
Insertitem Selection[i].max.y maxyarray (maxyarray.count+1)
Insertitem Selection[i].min.z minzarray
(minzarray.count+1)
)
)
Minx = amin minxarray
Maxx = amax maxxarray
Miny = amin minyarray
Maxy = amax maxyarray
Minz = amin minzarray
--Then create the group group01
group selection
--and parent the group to a temporal point helper
mypoint = point()
mypoint.position = [(minx + maxx)/2, (miny + maxy)/2,minz]
$group01.parent = mypoint
-- align the helper
mypoint.pos = mydesiredobject.pos
delete mypoint
--and finally explode the group if needed
ungroup $group01
-- mydesiredobject is a variable that i have not defined yet. This is the goal object for alignment.
I think you need to create a roolout with a pickbutton and a button.By clicking the pickbutton pick the desired object. Then declare it with mydesiredobject = getnodebyname mypickbutton.text
By pressing the simple button execute the script that I have written. I think you should say the pickbutton control to show the picked object as text over it. See the pickbutton properties help topic.

thanks a lot man.i really appreciate your detail reply.i gonna try it .
in the mean time i was using ".center ".it also works fine.

now i am thinking an weighted average center my be more suitable rather than only center.its possible by your method as you consider them each by each. :-)
thanks again.