afni.nimh.nih.gov

Hi Jayna,

Another possibility would be to decide on a y coordinate that
cuts off anterior from posterior. Then you could zero out
any part of the mask where the y value is too large.

E.g. to zero voxel with y greater than 12 (making this up):

3dcalc -a mask+tlrc -expr 'a*ispositive(12.1-y) -prefix ant.mask

That uses the y coordinate (assuming an RAI oriented dataset,
where positive y means posterior) to mask the original values.

See 3dcalc -help for more examples (such as #7).

- rick