topic Re: How to calculate cumulative sum using Lag function? in New SAS User

How to calculate cumulative sum using Lag function?

aman23 — Wed, 27 Feb 2019 09:22:06 GMT

How to calculate cumulative sum of below data using Lag function?

Name Marks

AA 50

BB 60

CC 70

DD 80

EE 90

FF 100

output should be:

Name Marks Cumulative marks

AA 50 50

BB 60 110

CC 70 180

DD 80 260

EE 90 350

FF 100 450

Re: How to calculate cumulative sum using Lag function?

RW9 — Wed, 27 Feb 2019 09:23:51 GMT

Use retain, its what it is for:

data want;
  set have;
  retain cumulative_marks;
  cumulative_marks=ifn(_n_=1,marks,sum(sumulative_marks,marks));
run;

Re: How to calculate cumulative sum using Lag function?

aman23 — Wed, 27 Feb 2019 09:27:30 GMT

yes using retain can get the result, but can it be done using Lag function???

Re: How to calculate cumulative sum using Lag function?

RW9 — Wed, 27 Feb 2019 09:36:48 GMT

Like any problem, it can be done, but why on earth would you want to go through that? You would need to create a lag statement specifically for each row of data as you cannot conditionally execute lag statements, so this would not work:

data want;
  set have;
  calc_marks=lag(calc_marks)+marks;
run;

If you try it you will get all kinds of weird results as the value used in the lag (which is a queue of values) does not work conditionally.

Use retain, its what its for.

Re: How to calculate cumulative sum using Lag function?

PaigeMiller — Wed, 27 Feb 2019 11:48:12 GMT

data want;
  set have;
  cumulative_marks+marks;
run;

You don't need anything more complicated.

Re: How to calculate cumulative sum using Lag function?

novinosrin — Wed, 27 Feb 2019 14:38:20 GMT

Hello @aman23 did this

  calc_marks=lag(calc_marks)+marks;

really work for your sample?