Using If else if then to recode variables

[zimu94681]

I have a dataset named "test" like this:

ID  A  B

1    1  1

2    1  1

3    1  0

4    0  1

5    -1  .

6    .   -1

7    .    .

8    .    .

9    .    .

10  .    .

I wrote a program to define a new variable "c"

data test1;

set test;

if a>0 or b>0 then c=1;

else if a<0 and b<0 then c=99;

else c=.

run;

I wish to see observation 7-10, c=. (missing)

But using the codes I wrote, I got all observation from 5-10, c=99 (observation 5 and 6, I want their c to be 99, but not observations 7-10)

Can someone modify my codes and make observation 7-10 column c to missing?

Many Thanks!!!

[novinosrin · Accepted solution]

HI @zimu94681 

Corrected version

data test;
input ID  A  B;
cards;
1    1  1
2    1  1
3    1  0
4    0  1
5    -1  .
6    .   -1
7    .    .
8    .    .
9    .    .
10  .    .
;

data test1;

set test;

if a>0 or b>0 then c=1;

else if .<a<0 or .<b<0 then c=99;

else c=.;

run;

[Tom]

Why not test for that first?

if missing(A) and missing(B) then c=.;
else if A>0 or B>0 then C=1;
else C=99;

Also what do you do when A or B is exactly zero?

[PaigeMiller]

Unstated in the above replies is that a missing numeric is considered to be less than zero. That's why your code produces a 99 for C. Either of the replies above have code to correct for this.

[zimu94681]

Does it mean that it's not a solvable situation? SAS can't distinguish negative values from missing value?

[Tom]

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@zimu94681 wrote:

Does it mean that it's not a solvable situation? SAS can't distinguish negative values from missing value?

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 SAS has 28 missing values. All missing values are treated as smaller than any actual number and they actually are ordered.  .Z is the largest missing value.

.Z < x < 0

[PaigeMiller]

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@zimu94681 wrote:

Does it mean that it's not a solvable situation? SAS can't distinguish negative values from missing value?

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That's not what it means. It means that missing is considered less than zero. Missing is also different than -1, and missing is different than -2, and so on.