calculate difference between last and first observation by subject

[Ronein]

Hello

I want to calculate for each customer the difference between wealth in first time and last time.

I want to create 2 wanted data set.

In "want1"  data set the difference between last and first will be dispalyed in last row.

In "Want2" data set only dispaly the last row with the information of wealth_first,wealth_last,difference

what is the way to do it please?

Data have;
Input Cust_ID  time  $ wealth;
cards;
1 2022-01 100
1 2022-02 90
1 2022-03 85
1 2022-04 130
2 2022-01 400
2 2022-02 410
2 2022-03 380
2 2022-04 270
2 2022-05 150
2 2022-06 40
;
Run;

Data want1;
Input Cust_ID  time  $ wealth dif;
1 2022-01 100 .
1 2022-02 90 .
1 2022-03 85 .
1 2022-04 130 30
2 2022-01 400 .
2 2022-02 410 .
2 2022-03 380 .
2 2022-04 270 .
2 2022-05 150  
2 2022-06 40 -360
;
Run;


Data want1;
Input Cust_ID  time  $   wealth_first  wealth_last dif;
1 2022-04 100 130 30
2 2022-06 400 40 -360
;
Run;

[Kurt_Bremser · Accepted solution]

Can be done in one step:

data want;
set have;
by cust_id;
retain wealth_first;
if first.cust_id then wealth_first = wealth;
if last.cust_id;
wealth_last = wealth;
dif = wealth_last - wealth_first;
drop wealth;
run;