assigning weights for clustering 2d objects

Hi,

what should be the approach to assign proper weights if we need to cluster objects based upon weighted data.. i.e I have n numbers of elements which need to be clusterize..

if (a,b) be the two dimensions of each object.. and w1 be the weight associated with a and w2 be the weight associated with b.. w1*a & w2*b

then how can I properly assign weights so that they can be clusterized based upon these 2d values