ranuni

Generate a dataset of random numbers generated with a uniform distribution U([0,1]). A macro version of SAS ranuni function.

%ranuni(dsn, sampsize, a=, b=, seed=0, int=no, lib=WORK);

Arguments

• dsn : name of the output dataset;
• sampsize : sample size, i.e. desired number of observations in the output dataset;
• a, b : (option) constants used to define the alternative distribution U([a,b]); if b is set and not a, then a=0; if a is set and not b, then b=10; default: neither a, nor b is set and only numbers ~ U([0,1]) are generated;
• seed : (option) seed of the pseudo-random numbers generator; if seed<=0, the time of day is used to initialize the seed stream; default: seed=0, i.e. a random seed is used;
• int : (option) boolean flag (yes/no) set to force integer numbers; default: int=no;
• lib : (option) name of the input library; by default: empty, i.e. WORK is used;

Returns

It will create the following variables, with size sampsize, in the output dataset dsn:

• u : uniformly distributed float numbers ~ U([0,1]),
• x : uniformly distributed float numbers ~ U([a,b]) if a and/or b are set,
• n : integers uniformly distributed ~ U([a,b]) if a and/or b are set and int=yes.

while an index variable i (sequence from 1 to sampsize) is also kept.

Examples

The following commands:

%let seed=1;
%let sampsize=10;
%ranuni(TMP, &sampsize, seed=&seed, int=yes);

allows us to generate (since we use a fixed seed >0) the table TMP of pseudo-random numbers below:

1	u	n
1	0.1849625698	2
2	0.9700887157	10
3	0.3998243061	4
4	0.2593986454	2
5	0.9216025779	10
6	0.9692773498	10
7	0.5429791731	5
8	0.5316917228	5
9	0.0497940262	0
10	0.0665665516	0

See %_example_ranuni for examples.

Note

In short, this macro runs the following DATA step:

DATA &lib..&dsn;
    do i = 1 to &sampsize;
        u = ranuni(&seed);
        %if not %macro_isblank(a) and not %macro_isblank(b) %then %do;
            %if %upcase(&int)=YES %then %do;
                n = &a + floor((1+&b-&a)*u);
            %end;
            %else %do;
                x = &a + (&b-&a)*u;      
            %end;
        %end;
        output;
    end;
run;

See also

RANUNI, RAND.