How exactly "in" and "not in" works in tuples?

General Usage
1

Hi all,

I’m trying to check some belonging conditions over some tuples. One set of tuples are numeric like (2,8) and the others are combined with text (2,8,'e','f').

I want to check for every numeric pair their existance in the 4-mixed tuples. So, I did this:

reduce(union, (2,8))
2-element Vector{Int64}:
  2
 8

reduce(union, (2,8, "e", "f"))
4-element Vector{Any}:
 2
 8
  'e': ASCII/Unicode U+0065 (category Ll: Letter, lowercase)
  'f': ASCII/Unicode U+0066 (category Ll: Letter, lowercase)


reduce(union,(2,8)) in reduce(union, (2,8, "e", "f"))
false

Then, why reduce(union,(2,8)) in reduce(union, (2,8, "e", "f")) return false?

1 Like
2 
help?> in
...
  in(item, collection) -> Bool
  ∈(item, collection) -> Bool

  Determine whether an item is in the given collection, in the sense 
  that it is == to one of the values generated by iterating over the 
  collection.
....

julia> in(reduce(union,(2,8)), reduce(union, (2,8, "e", "f")))
false

julia> map(in,reduce(union,(2,8)), reduce(union, (2,8, "e", "f")))
2-element Vector{Bool}:
 1
 1

Does this answer your question?

1 Like
3

You might be looking for issubset (can also be written as the binary operator ⊆ (\subseteq)).

julia> issubset((2,8), (2,8,"e","f"))
true

julia> (2,8) ⊆ (2,3,4)
false

If you still also need to convert your tuples to vectors, you can use collect – no need to do reduce(union,...).

julia> collect((2,8))
2-element Vector{Int64}:
 2
 8
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