topic Re: substract data from different rows in SAS Programming

substract data from different rows

mona4u — Wed, 22 Jun 2022 01:33:15 GMT

Hi All,

Below is an example of what I'm trying to achieve. My goal is to get the variable diff.

X	Y	LAG	DIFF
1	A
2	A	1	1
3	A	2	1
4	A	3	1
5	A	4	1
1	B
2	B	1	1
3	B	2	1
4	B	3	1
5	B	4	1

Mona

Re: substract data from different rows

Reeza — Wed, 22 Jun 2022 02:25:15 GMT

Why is the first diff 1 when there's no previous value?
If it's always 1 why is this needed? It would be good to include a use case that illustrates a different scenario.

I suspect this is what you're after?

data want;
set have;
by y;
_dif = dif(x);
_lag = lag(x);
if first.y then call missing(_dif, _lag);
run;

@mona4u wrote:

Hi All,

Below is an example of what I'm trying to achieve. My goal is to get the variable diff.

X Y LAG DIFF

1 A

2 A 1 1

3 A 2 1

4 A 3 1

5 A 4 1

1 B

2 B 1 1

3 B 2 1

4 B 3 1

5 B 4 1

Mona

Re: substract data from different rows

mona4u — Wed, 22 Jun 2022 14:52:49 GMT

because I don't want to subtract different group values.

the diff value not always 1 this is just dummy

Re: substract data from different rows

Reeza — Wed, 22 Jun 2022 15:04:25 GMT

Did you try the code posted?

I'm assuming groups are defined by Y as you never stated. I'm assuming you want the lag of the variable X, also not specifically stated.

If the above is true the answer should be correct. Use the DIF/LAG function and reset at the first of each group.