Hi carmi,
If you are using OriginPro, you can try the following procedure to use the Cluster gadget: (Let's assume the worksheet hasA(X), B(Y), and you made a scatter plot from it.)1) Add a column (C) for the color indexing to the worksheet.
2) Double-click the plot, and in Plot Details dialog, set the Symbol Color to Index:Col(C)
3) Using Cluster tool, mask the area of a group (as many times as you like to cover all desired regions).
(You can press "Change Mask Color" button to choose the masking color to distinguish.)
4) Use Set Column Values tool for this new 3rd column with the formula:
col(2)<i>==1?<color#>:col(3)[i] with the Recalculation Mode=None
(See the list of colors at http://wiki.originlab.com/~originla/ltwiki/index.php?title=LabTalk:List_of_Colors )
5) Right-click the Y column, and choose "Mask>Remove" flyout to clear the mask
6) Repeat 3)-5) to cover all groups.
Hope this also helps.
--Hideo Fujii
OriginLab