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Value start from begining

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Frequent Contributor
Posts: 84
Accepted Solution

Value start from begining


data have;
input number;
cards;
12
10
8
6
4
2
run;

 

 

data want;
set have;
lag_d = lag(number) - number;
run;

 

when i run this code i am getting like this 

 

 

Obs number lag_d
1 12 .
2 10 2
3 8 2
4 6 2
5 4 2
6 2 2

 

but i need the ouput like this insted of staring . i need the valus from frist row

 

Obs number lag_d
1 12 2
2 10 2
3 8 2
4 6 2
5 4 2
6 2 0

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Solution
‎03-31-2017 02:10 PM
Super User
Posts: 10,023

Re: Value start from begining


data have;
input number;
cards;
12
10
8
6
4
2
;
run;

data want;
 merge have have(keep=number rename=(number=_n) firstobs=2);
 lag_d=number-_n;
 if missing(lag_d) then lag_d=0;
 drop _n;
run;

View solution in original post


All Replies
PROC Star
Posts: 735

Re: Value start from begining

What you want to do is to simulate a lead function. It can be done like this

 

data have;
input number;
cards;
12
10
8
6
4
2
run;
 
data have;
   set have;

   if eof=0 then
      set have (firstobs=2 keep=number rename=(number=lead_number)) end=eof;
   else lead_number=.;

   lag_d = number - lead_number;
run; 

Bear in mind though, that the last value of your lag_d variable will be missing with this solution, which I think is more approprate than it being zero, since you do not know the next value of number. This can be corrected fairly easily though Smiley Happy

Solution
‎03-31-2017 02:10 PM
Super User
Posts: 10,023

Re: Value start from begining


data have;
input number;
cards;
12
10
8
6
4
2
;
run;

data want;
 merge have have(keep=number rename=(number=_n) firstobs=2);
 lag_d=number-_n;
 if missing(lag_d) then lag_d=0;
 drop _n;
run;

☑ This topic is solved.

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