This may be an easy question for most of you, but any prompt clues/hints/examples would be really appreciated. My dataset includes a various number of records (by time points) for a variable by subject. I use xyplot to plot line/symbol graphs of the variable at each available time point by each subject on the same plot (see attached as an example). How to suppress those symbols with no available time points (e.g. symbols for subject 1001 study days 5, 6, 7)? Below is a quick example of data: Subject Study Day % CD8 response 1001 1 0.23 1001 2 0.25 1001 3 0.27 1001 4 0.29 1001 8 0.29 1002 1 0.23 1002 2 0.25 1002 3 0.27 1002 4 0.29 1002 5 0.23 1002 6 0.25 1002 7 0.27 1002 8 0.29 1003 1 0.23 1003 2 0.25 1003 3 0.27 1003 4 0.29 1003 5 0.23 1003 6 0.25 1003 7 0.27 1003 8 0.29 1004 1 0.23 1004 2 0.25 1004 3 0.27 1004 4 0.29 1004 8 0.29 Thanks a lot in advance! James