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

findin() doesn't give you a boolean mask, but you can easily use it to subset an array/DataFrame for values that are contained in another array:

julia> giant_list[findin(giant_list, good_letters)]
1-element Array{String,1}:
 "a"