Generate RANDOM and UNIQUE numbers for a specific range

Question

Hello, 
 I am trying to randomly sample x amount of rows from a CDT by generating x random numbers in the range 1:length(myCdt). The issue I am getting is that some of these random numbers are repeated. 
 Is there a way to generate random numbers in a given interval and have them be unique? 
 
 Here is what I have so far: 
 local!randomNumbers:if( 
 length(local!query)>15, 1+ tointeger(rand(15) * length(local!query)), local!query, 
 ),

Peter Lewis · Answer

There might be a simpler way to do this, but this solution should guarantee a random order without repeated data regardless of how many values you have: 
 a!localVariables(
 local!numberOfValues: 15,
 local!randomData: rand(local!numberOfValues),
 local!index: a!forEach(
 items: local!randomData,
 expression: rank(
 fv!item,
 local!randomData
 )
 ),
 index(
 enumerate(local!numberOfValues)+1,
 local!index
 )
) 
 Basically you just generate a list of random decimals and then find the rank in the list of each of them. That will guarantee that all values are used and that they don't repeat!

Amaan Shekh · Answer

here is the recursive approach for getting x amount of unique numbers between a define range a!localVariables(
 local!random: ri!min + tointeger(rand() * (ri!max - ri!min)),
 local!arrray: append(ri!array, local!random),
 if(
 length(union(local!arrray, local!arrray)) >= ri!count,
 local!arrray,
 rule!CP_getRandomList(
 min: ri!min,
 max: ri!max,
 count: ri!count,
 array: union(local!arrray, local!arrray)
 )
 )
)
// NOTE - count < max - min , 
 more insights ->

Generate RANDOM and UNIQUE numbers for a specific range

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