Remove Duplicates- Times Series Data

[kaythth]

Hello! 

I am running my head into a wall trying to figure out how to remove select duplicates from my dataset.  I want to track locations by a unique identifier, but I dont want to include repeat data from consecutive entries from the same location.  Here is an example of the data I have: 

ID       coll_Dt         Fac

1        1/12/17         A

1        1/20/17         A

1        5/6/17           B

1        6/5/17           A 

1        7/8/17           C

2        1/26/17         B

2        2/5/17           B

2        4/15/17         C

2        5/2/17           C 

2        5/29/17         B

3        2/20/17          A

3        4/19/17          B

3        5/16/17          B

3        6/8/17            C

3         8/1/17           A

And this is what I would like the location to look like:  (the entries in bold above removed)

ID       coll_dt         Fac

1        1/12/17         A

1        5/6/17           B

1        6/5/17           A 

1        7/8/17           C

2        1/26/17         B

2        4/15/17         C

2        5/29/17         B

3        2/20/17         A

3        4/19/17         B

3        6/8/17           C

3         8/1/17          A

 Nodupkey doesnt work becuase I want to keep duplicate locations for the same ID#- just not when they appear consecutively.  I have tried using: 

data a; set a; 

by id coll_dt fac; 

if first.fac; 

run; 

but that doesnt seem to work either. 

Please help! 

Thank you 🙂 

[Reeza]

I think you need the NOTSORTED option.

data a; set a; 
by id coll_dt fac NOTSORTED; 
if first.fac; 
run; 

[kaythth]

That did not work either, sadly 😞 

[ballardw · Accepted solution]

data want;

set a;

by id fac NOTSORTED coll_dt ;

if first.fac;

run;

[kaythth]

Thank you!!