Get duplicates from array

Hi, Please try to use this

a!localVariables(
  local!a:{1,2,2,3,3},
  a!flatten(a!forEach(
    items: union(local!a,local!a),
    expression: if(
      length(wherecontains(fv!item,local!a))>1,
      fv!item,
      {}
    )
  ))
)

This seems to work, too.

a!localVariables(
  local!input: { 1, 2, 2, 3, 3 },
  local!output: index(local!input, a!forEach(union(local!input, local!input), index(wherecontains(fv!item, local!input), 2, {}))),
  local!output
)

Don't use, but it may be of interest:

a!localVariables(
  local!input: { 1, 2, 2, 3, 3 },
  local!output: index(local!input, where(a!forEach(local!input, fv!index>wherecontains(fv!item, local!input)[1]))),
  local!output
)

Note this last example will need a union() on the local!output as it duplicates values with more than 2 occurrences.