Thanks, All. That's great.

On Fri, Jul 31, 2009 at 10:01 AM, Paul Dorfman <sashole@bellsouth.net>wrote:

> OR Stats, > > Frankly, what you have described puzzles me. It stands to reason that the > *first* instance of a duplicate key record is kept, and in my experience > it has unfailingly been so, which also pertains to your data sample. When > I run it, I get Y=100 and Y=300, just as I expect. As I understand, it is > assured by EQUALS proc sort option. If I really need to make sure that > relative order of an unsorted file is the same as that of the sorted file, > I code it explicitly, lest the system has the default set to NOEQUALS. > > But your task, IIUC, is to select, from each date BY-group, the record > with the maximal Y. It is then either a 2-step process, as Joe has > suggested, for example, > > data a ; > input date: mmddyy8. Y ; > cards ; > 1/3/09 50 > 1/5/09 100 > 1/5/09 200 > 1/6/09 300 > 1/6/09 10 > ; > run ; > > proc sort data = a out = b ; > by date Y ; > run ; > > data c ; > set b ; > by date ; > if last.date ; > run ; > > Or it can be a 1-step SQL process (which is, of course, still a 2-step > process behind-the-scenes): > > proc sql ; > create table c as > select date > , max (Y) as Y > from a > group date > order date > ; > quit ; > > Or it can be a 1-step proc means/summary just as well: > > proc means data = a nway noprint ; > class date ; > var Y ; > output out = c (drop = _:) max= ; > run ; > > Kind regards > ------------ > Paul Dorfman > Jax, FL > ------------ > > > > On Fri, 31 Jul 2009 09:17:24 -0500, OR Stats <stats112@GMAIL.COM> wrote: > > >Hello: > > > >In PROC SORT, can we choose which duplicate record to keep by a > conditional > >statement? > > > >For example, my data looks like this > > > >Date Y > >1/3/09 50 > >1/5/09 100 > >1/5/09 200 > >1/6/09 300 > >1/6/09 10 > > > >For 1/5, Y=200 is kept and Y=100 is deleted; whereas for 1/6, Y=300 is > kept > >and Y=10 is deleted. The final data would look like the following > >Date Y > >1/3/09 50 > >1/5/09 200 > >1/6/09 300 > > > >Thanks! >