Is there a good implementation of a BiDict (invertable Dict)

General Usage
,
1

I need a lookup table that works in both directions for saving and loading a custom file.
Therefore I thought a dictionary that also used the values as keys might be handy.

Is there a good implementation for this?

My current attempt looks like this:

struct BiDict
    key1        
    key2
end

function Base.getindex(bd::BiDict,::Val{1},ind)
    bd.key2[findfirst(isequal(ind),bd.key1)]
end

function Base.getindex(bd::BiDict,::Val{2},ind)
    bd.key1[findfirst(isequal(ind),bd.key2)]
end

It can be used to search in both directions using the first index, although I am not sure how to best avoid using Val.

julia> lookup = BiDict([2,4,3,1],[:s,:j,:e,:t])
BiDict([2, 4, 3, 1], [:s, :j, :e, :t])

julia> lookup[Val(1),4]
:j

julia> lookup[Val(2),:j]
4
2

Might be what you’re after

1 Like
3

This looks good. Thank you!
I am just wondering if it really is necessary to store two sets as well as two dicts to do this.