Julia Programming Projects

Working with dictionaries

As we've already seen, we can index into a Dict using the square bracket notation:

julia> d = Dict(:foo => 1, :bar => 2) 
Dict{Symbol,Int64} with 2 entries: 
  :bar => 2 
  :foo => 1 julia> d[:bar] 2 

Attempting to access a key that has not been defined will result in a KeyError, as follows:

julia> d[:baz] 
ERROR: KeyError: key :baz not found 

To avoid such situations, we can check if the key exists in the first place:

julia> haskey(d, :baz) 
false 

As an alternative, if we want to also get a default value when the key does not exist, we can use the following:

julia> get(d, :baz, 0) 
0 

The get function has a more powerful twin, get!, which also stores the searched key into the Dict, using the default value:

julia> d Dict{Symbol,Int64} ...