File storage

using Graphs
using MetaGraphsNext

MGFormat

MetaGraphsNext.jl overloads Graphs.savegraph to write graphs in a custom format called MGFormat, which is based on JLD2. It is not very readable, but it does give the right result when we load it back. This requires JLD2 to be loaded as well.

using JLD2

example = MetaGraph(Graph(), Symbol);

example2 = mktemp() do file, io
    savegraph(file, example)
    loadgraph(file, "something", MGFormat())
end

example2 == example

true

DOTFormat

MetaGraphsNext.jl also support the more standard DOT encoding, which is used as follows.

simple = MetaGraph(Graph(), Symbol);

simple[:a] = nothing;
simple[:b] = nothing;
simple[:a, :b] = nothing;

simple_str = mktemp() do file, io
    savegraph(file, simple, DOTFormat())
    read(file, String)
end

simple_str_true = """
graph T {
    "a"
    "b"
    "a" -- "b"
}
"""

simple_str == simple_str_true

true

complicated = MetaGraph(
    DiGraph();
    label_type=Symbol,
    vertex_data_type=Dict{Symbol,Int},
    edge_data_type=Dict{Symbol,Int},
    graph_data=(tagged=true,),
);

complicated[:a] = Dict(:code_1 => 1, :code_2 => 2);

complicated[:b] = Dict(:code => 2);

complicated[:a, :b] = Dict(:code => 12);

complicated_str = mktemp() do file, io
    savegraph(file, complicated, DOTFormat())
    read(file, String)
end

complicated_str_true = """
digraph G {
    tagged = true
    "a" [code_1 = 1, code_2 = 2]
    "b" [code = 2]
    "a" -> "b" [code = 12]
}
"""

"digraph G {\n    tagged = true\n    \"a\" [code_1 = 1, code_2 = 2]\n    \"b\" [code = 2]\n    \"a\" -> \"b\" [code = 12]\n}\n"

with_spaces = MetaGraph(
    DiGraph();
    label_type=String,
    vertex_data_type=Dict{Symbol,String},
    edge_data_type=Dict{Symbol,String},
)

with_spaces["a b"] = Dict(:label => "A B")

with_spaces["c d"] = Dict(:label => "C D")

with_spaces["a b", "c d"] = Dict(:label => "A B to C D")

with_spaces_str = mktemp() do file, io
    savegraph(file, with_spaces, DOTFormat())
    read(file, String)
end

with_spaces_str_true = """
digraph G {
    "a b" [label = "A B"]
    "c d" [label = "C D"]
    "a b" -> "c d" [label = "A B to C D"]
}
"""

with_spaces_str == with_spaces_str_true

true

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