generate unique random numbers

[vzeufack]

Yeah that is my real issue.

I do realize that the RANDOM() function hardly generates same numbers. But, how do I do if I want unique random numbers within a specific range (let say between 1 and 10)?

Best regards,
Vannel,

[rtaylor]

Vannel,

And I just heard about this function, that does it all:

Code: Select all

IMPORT Std;
ds := DATASET(1000*1000, TRANSFORM({UNSIGNED4 r},
                            SELF.r  := STD.System.Util.GetUniqueInteger()));
COUNT(ds);   //a million                                       
out := DEDUP(SORT(ds,r),r);
COUNT(out);  //still a million

HTH,

Richard

[vzeufack]

Sorry if I may have not set my question clearly. I think this function generates as many unique integers as you specify right?
I am looking for a function which can generate 10 random numbers taken from the range [1 - 1000] for example. So, the general problem is to generate X random numbers taken from the range [a - b].

[vzeufack]

And those X random numbers lying between [a - b] have to be unique.

[DSC]

Yeah that is my real issue. I do realize that the RANDOM() function hardly generates same numbers. But, how do I do if I want unique random numbers within a specific range (let say between 1 and 10)?

Are you confusing "random" with "shuffled"? Random numbers can repeat. Dice have six numbers on them, and if you throw one die the likelihood of any number showing face-up is 1/6. If you threw one die twice and wound up with "five" both times, that is still random even though you got the same result.

In case you're looking for shuffled numbers, here is one way to do that:

Code: Select all

NUM_COUNT := 10;

ds := DATASET
    (
        NUM_COUNT,
        TRANSFORM
            (
                {
                    UNSIGNED4   rand,
                    UNSIGNED4   num
                },
                SELF.rand := RANDOM(),
                SELF.num := COUNTER
            )
    );

// sort the dataset by the random numbers
sortedByRandom := SORT(ds, rand);

// strip out the random numbers
onlyNums := TABLE(sortedByRandom, {num});

OUTPUT(onlyNums);

The result will be the unique numbers 1-10 in a random order.