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04-10-2017 03:09 PM

Hi everyone,

I would like to generate all possible combinations of three variables each with values 0 or 1 e.g. following using a data step

000

001

010

100

011

101

110

111

what will be a good way to do it?

Accepted Solutions

Solution

04-10-2017
09:37 PM

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04-10-2017 09:22 PM - edited 04-10-2017 11:22 PM

So maybe something like this.

```
data want;
array p[2] _temporary_ (0 1);
array x[3];
do _n_=0 to dim(p)**dim(x)-1;
do i=1 to dim(x);
x(i)=p(1+mod(int(_n_/(dim(p)**(i-1))),dim(p))) ;
end;
output;
end;
drop i ;
run;
```

All Replies

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04-10-2017 03:21 PM

Check out the ALLCOMB function in SAS. Designed just for such a thing!

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04-10-2017 06:50 PM

Thanks, it's a nice function. But the problem is I have n=2 (0 or 1) but k=3 which doesn't work for ALLCOMB.

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04-10-2017 07:06 PM

A not terribly bright solution

data _null_; do i='0','1'; do j='0','1'; do k='0','1'; comb=cats(i,j,k); put comb=; end; end; end; run;

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04-10-2017 07:27 PM

Thanks. The need is to have three distinct columns rather than a single column with all possible combinations.

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04-10-2017 03:36 PM

These combinations are just a sequence of binary numbers. You don't need any data to do that:

data want;

do i=0 to 7;

result = put(i, binary3.);

output;

end;

drop i;

run;

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04-10-2017 07:03 PM

Thanks, this is a nice little trick. I will have to have 3 different columns for all combinations of 0 or 1.

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04-10-2017 07:35 PM

For three it is simple.

```
data want;
do a=0,1; do b=0,1; do c=0,1;
output;
end; end; end;
run;
```

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04-10-2017 07:49 PM

Great! This has promise. If I have two arrays

P = (0 1) and x = (x1 x2 x3) where each of x takes values 0 or 1, how would you do it?

P = (0 1) and x = (x1 x2 x3) where each of x takes values 0 or 1, how would you do it?

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04-10-2017 08:07 PM

Not sure what you are talking about at this point. If you have four variables named P, X1 , X2, and X3 then you could build all combinations using similar DO loops. If you have two tables and want to join them to produce all possible combinations then PROC SQL does a good job.

```
proc sql ;
create table want as
select *
from P, X
;
quit;
```

If you really have two vectors and what to manipulate them then use PROC IML. You can do lots of matrix manipulation using a language designed to work with matrices.

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04-10-2017 08:18 PM

Thanks, I have the following data -

Data a;

Array p[2] (0 1);

Array x[3];

I would like the data step operations to produce 8 rows with the unique combinations.

Data a;

Array p[2] (0 1);

Array x[3];

I would like the data step operations to produce 8 rows with the unique combinations.

Solution

04-10-2017
09:37 PM

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04-10-2017 09:22 PM - edited 04-10-2017 11:22 PM

So maybe something like this.

```
data want;
array p[2] _temporary_ (0 1);
array x[3];
do _n_=0 to dim(p)**dim(x)-1;
do i=1 to dim(x);
x(i)=p(1+mod(int(_n_/(dim(p)**(i-1))),dim(p))) ;
end;
output;
end;
drop i ;
run;
```

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04-10-2017 09:37 PM

This is cool. I have devised a similar solution (but less technical) based on Astounding's proposal.

data a;

array p[2] _temporary_;

array x[3];

do i=1 to dim(p)**dim(x);

result = put(i, binary3.);

do j=1 to 3;

x[j]=substr(result,j,1);

end;

output;

end;

drop i j;

run;

data a;

array p[2] _temporary_;

array x[3];

do i=1 to dim(p)**dim(x);

result = put(i, binary3.);

do j=1 to 3;

x[j]=substr(result,j,1);

end;

output;

end;

drop i j;

run;