Dict is the standard dictionary. Its implementation uses
hashas the hashing function for the key, andisequalto determine equality. Define these two functions for custom types to override how they are stored in a hash table.
I plot in my neo4j db the sub-graph about Dict type to get a better understand of its type hierarchy:
Dict is quite similar to dictionary in Python. So I just show some of my test code below.
d1 = Dict("a"=> 11, "b" => 22, "c" => 33)
println("d1: $d1, type: ", typeof(d1))
ks = keys(d1) # get all keys of dict
println("ks: $ks, type: ", typeof(ks))
arr_ks = collect(keys(d1)) # put all keys into a list
arr2_ks = [k for (k,v) in d1] # array comprehension from a dict
println("arr_ks: $arr_ks, arr2_ks: $arr2_ks")
vs = values(d1)
println("vs: $vs, type: ", typeof(vs))
arr_vs = [v for (k,v) in d1] # array comprehension from a dict
println("arr_vs: $arr_vs")
d1["d"] = 44 # add new item to a dict
for (key, val) in d1
println(" key: $key, value: $val")
end
println(haskey(d1, "a")) # to check if dict has a certain key
pop!(d1, "d") # remove an item
println("d1: $d1, type: ", typeof(d1))
println(haskey(d1, "d"))
Execution output:
d2 = Dict(:a=> 11, :b => 22, :c => 33) # symbol-keys
println("d2: $d2")
println(keys(d2))
for (key, val) in d2
println(" key: $key, value: $val")
end
println(d2[:a])
try
d2["d"] = 44 # try to add a string-key to a dict with symbol-keys
println("d2: $d2")
catch e
print(e)
end
Execution output:
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