topic Re: Calculate running sum per ID in SAS Procedures

Calculate running sum per ID

Keith0001 — Fri, 02 Jan 2015 16:07:00 GMT

Hi all,

I'm new at using SAS and am not proficient in BASE SAS. I normally use Proc SQL for my needs.

However, it seems the LAG function is not available for Proc SQL so I'm having to use Base, which is giving me problems.

I'm trying to calculate a running sum of a value over an ID.

This is my example dataset:

data INPUT;

input ID $2. LINENR VALUE;

datalines;

A 1 1

A 2 5

A 3 2

A 4 8

B 1 4

B 2 3

B 3 4

C 1 2

D 1 7

E 1 6

E 2 3

E 3 1

E 4 7

E 5 4

F 1 2

G 1 8

G 2 9

;

run;

The output I'm looking for would be in Variable1.

ID	LINENR	VALUE	VAR1
A	1	1	1
A	2	5	6
A	3	2	8
A	4	8	16
B	1	4	4
B	2	3	7
B	3	4	11
C	1	2	2
D	1	7	7
E	1	6	6
E	2	3	9
E	3	1	10
E	4	7	17
E	5	4	21
F	1	2	2
G	1	8	8
G	2	9	17

I have already sorted my dataset by ID and Linenumber.

My code is :

data OUTPUT;

set INPUT;

if ID = lag1(ID) then VAR1 = VALUE + lag1(VALUE) ;

else VAR1 = VALUE ;

if ID = lag1(ID) then VAR2 = VALUE + lag1(VAR2) ;

else VAR2 = VALUE ;

run;

A simpel lag value adds the previous value to the current value for an ID, in VAR1. But somehow the 2nd row of the output shows an empty value. Why is this ?

As I am looking for a running sum within an ID I also need to add the other values. VAR2 is an attempt to do this. But it seems I cannot reference the variable itself.

How do I fix my code so I have a running sum within an ID value ?

Thank you

Re: Calculate running sum per ID

stat_sas — Fri, 02 Jan 2015 16:14:16 GMT

data want;

set input;

by id;

if first.id then var1=0;

var1+value;

run;

Re: Calculate running sum per ID

mohamed_zaki — Fri, 02 Jan 2015 16:34:36 GMT

Regarding your desired output

data OUTPUT (drop=x);

set INPUT;

by ID;

x=lag1(Value);

If first.ID then VAR1=VALUE;

Else VAR1 = x + Value ;

run;

Re: Calculate running sum per ID

Keith0001 — Fri, 02 Jan 2015 16:35:06 GMT

Thank you stat@sas , your answer works.

Mohamed, thank you. However your answer gives the wrong result. Its only adding the current record and the previous one per ID.

Re: Calculate running sum per ID

Ksharp — Sat, 03 Jan 2015 07:45:22 GMT

You also could get it by SQL ,since you have already COUNT variable LINENR .

data INPUT;
  input ID $2. LINENR VALUE;
  datalines;
A 1 1
A 2 5
A 3 2
A 4 8
B 1 4
B 2 3
B 3 4
C 1 2
D 1 7
E 1 6
E 2 3
E 3 1
E 4 7
E 5 4
F 1 2
G 1 8
G 2 9
;
run;
proc sql;
 create table want as
  select *,(select sum(value) from input where id=a.id and linenr le a.linenr) as var1
   from input as a;
quit;

Xia Keshan

Re: Calculate running sum per ID

Keith0001 — Mon, 05 Jan 2015 16:27:31 GMT

Hi Xia,

Thank you, this works very well for my requirements.