如何在Julia中翻译字典？

Question

如果我有这样一个字典作为

my_dict = Dict(
    "A" => "one", 
    "B" => "two", 
    "C" => "three" 
) 

什么是扭转键/值映射关系的最佳方式？

Answer 1

的一种方法是通过遍历键/值对，沿途交换他们使用的理解来构建新字典：

julia> Dict(value => key for (key, value) in my_dict) 
Dict{String,String} with 3 entries: 
    "two" => "B" 
    "one" => "A" 
    "three" => "C" 

当交换键和值，您可能希望保留请记住，如果my_dict具有重复值（例如"A"），则新字典可能包含的键较少。另外，新字典中按键"A"定位的值可能不是您期望的值（Julia的字典不以任何容易确定的顺序存储其内容）。

Answer 2

假设你不必担心重复值碰撞钥匙，map与reverse你可以使用：

julia> my_dict = Dict("A" => "one", "B" => "two", "C" => "three") 
Dict{String,String} with 3 entries: 
    "B" => "two" 
    "A" => "one" 
    "C" => "three" 

julia> map(reverse, my_dict) 
Dict{String,String} with 3 entries: 
    "two" => "B" 
    "one" => "A" 
    "three" => "C" 

Answer 3

使这个一会儿回来，可能有冲突值

function invert_dict(dict, warning::Bool = false) 
    vals = collect(values(dict)) 
    dict_length = length(unique(vals)) 

    if dict_length < length(dict) 
     if warning 
      warn("Keys/Vals are not one-to-one") 
     end 

     linked_list = Array[] 

     for i in vals 
      push!(linked_list,[]) 
     end 

     new_dict = Dict(zip(vals, linked_list)) 

     for (key,val) in dict 
      push!(new_dict[val],key) 
     end 
    else 
     key = collect(keys(dict)) 

     counter = 0 
     for (k,v) in dict 
      counter += 1 
      vals[counter] = v 
      key[counter] = k 
     end 
     new_dict = Dict(zip(vals, key)) 
    end 

    return new_dict 
end 

词典

使用此如果如果一个关键成为重复，你将有一个列表与所有值，所以没有数据将会丢失，即

julia> a = [1,2,3] 
julia> b = ["a", "b", "b"] 

julia> Dict(zip(a,b)) 
Dict{Int64,String} with 3 entries: 
    2 => "b" 
    3 => "b" 
    1 => "a" 

julia> invert_dict(ans) 
Dict{String,Array} with 2 entries: 
    "b" => Any[2,3] 
    "a" => Any[1]