## Computing third variable using id and another variable

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Super Contributor
Posts: 328

# Computing third variable using id and another variable

Data A;

Imput id A;

Cards;

1. 4

1  7

1. 11
2. 1

2    10

3   11

3  13

Run;

I want to create a  variable B such
that

1. 4         4-4=0(id=1)

1    7           7-4=3

1. 11       11-7=4
2. 1         1-1=0(id=2)

2  10          10-1=9

3 11            11-11=0(id=3)

3  13          13-11=2(id=3)

Accepted Solutions
Solution
‎11-10-2014 01:27 PM
Posts: 1,270

## Re: Computing third variable using id and another variable

data want;

set A;

by id;

B=a-lag(a);

if first.id then B=0;

run;

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Solution
‎11-10-2014 01:27 PM
Posts: 1,270

## Re: Computing third variable using id and another variable

data want;

set A;

by id;

B=a-lag(a);

if first.id then B=0;

run;

Super User
Posts: 6,785

## Re: Computing third variable using id and another variable

Not as well known, but equally effective here, is a cousin of the LAG function.  These two statements produce identical results:

B=a-lag(a);

B=dif(a);

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