Vectorized “in” function in julia?

Question

I often want to loop over a long array or column of a dataframe, and for each item, see if it is a member of another array. Rather than doing

giant_list =          


        

Answer 1

You can vectorize in quite easily in Julia v0.6, using the unified broadcasting syntax.

julia> in.(giant_list, (good_letters,))
3-element Array{Bool,1}:
  true
 false
 false

Note the scalarification of good_letters by using a one-element tuple. Alternatively, you can use a Scalar type such as the one introduced in StaticArrays.jl.

Julia v0.5 supports the same syntax, but requires a specialized function for scalarificiation (or the Scalar type mentioned earlier):

scalar(x) = setindex!(Array{typeof(x)}(), x)

after which

julia> in.(giant_list, scalar(good_letters))
3-element Array{Bool,1}:
  true
 false
 false