Returns default GraphML serialization options.

The options control XML formatting:

• indent: Number of spaces for indentation (default: 2)
• include_xml_declaration: Whether to include XML declaration (default: true)

Example

iex> {:graphml_options, indent, include_xml_declaration} = Yog.IO.GraphML.default_options()
iex> indent
2
iex> include_xml_declaration
true

Deserializes a GraphML string to a graph using default conversion.

Node and edge attributes are stored as-is in maps. For custom data structures, use deserialize_with/3.

Time Complexity: O(V + E) where V is nodes and E is edges

Returns

• {:ok, graph} on success
• {:error, {:parse_error, reason}} on parsing failure

Example

iex> xml = """
...> <?xml version="1.0" encoding="UTF-8"?>
...> <graphml xmlns="http://graphml.graphdrawing.org/xmlns">
...>   <graph id="G" edgedefault="directed">
...>     <node id="1"><data key="label">Alice</data></node>
...>     <node id="2"><data key="label">Bob</data></node>
...>   </graph>
...> </graphml>
...> """
iex> {:ok, graph} = Yog.IO.GraphML.deserialize(xml)
iex> Yog.Model.node_count(graph)
2

Performance Note

For large files, parsing automatically uses the fast saxy parser when available, falling back to :xmerl otherwise. See module documentation for performance details.

Deserializes a GraphML string into a graph with custom data mappers.

This function allows you to transform the raw GraphML attributes into custom Elixir data structures as the graph is built.

Time Complexity: O(V + E) where V is nodes and E is edges

Parameters

• node_folder - Function to transform node attributes to node data (attrs :: map) -> node_data
• edge_folder - Function to transform edge attributes to edge data (attrs :: map) -> edge_data
• xml - The GraphML XML string to parse

Returns

• {:ok, graph} on success
• {:error, {:parse_error, reason}} on parsing failure

Example

iex> xml = """
...> <?xml version="1.0" encoding="UTF-8"?>
...> <graphml xmlns="http://graphml.graphdrawing.org/xmlns">
...>   <graph id="G" edgedefault="directed">
...>     <node id="1">
...>       <data key="name">Alice</data>
...>       <data key="age">30</data>
...>     </node>
...>     <node id="2">
...>       <data key="name">Bob</data>
...>       <data key="age">25</data>
...>     </node>
...>     <edge source="1" target="2">
...>       <data key="weight">5</data>
...>     </edge>
...>   </graph>
...> </graphml>
...> """
iex> node_folder = fn attrs ->
...>   %{name: Map.get(attrs, "name"), age: String.to_integer(Map.get(attrs, "age", "0"))}
...> end
iex> edge_folder = fn attrs ->
...>   String.to_integer(Map.get(attrs, "weight", "1"))
...> end
iex> {:ok, graph} = Yog.IO.GraphML.deserialize_with(node_folder, edge_folder, xml)
iex> Yog.Model.node_count(graph)
2

Reads a graph from a GraphML file using default conversion.

This is a convenience function that combines File.read/1 with deserialize/1.

Time Complexity: O(V + E) + file I/O

Parameters

• path - File path to read from

Returns

• {:ok, graph} on success
• {:error, reason} on file read or parse failure

Example

# Read a GraphML file exported from Gephi or NetworkX
{:ok, graph} = Yog.IO.GraphML.read("social_network.graphml")

# Check what we loaded
IO.puts("Nodes: #{Yog.Model.node_count(graph)}")
IO.puts("Edges: #{Yog.Model.edge_count(graph)}")

Reads a graph from a GraphML file with custom data mappers.

Use this when you want to transform GraphML attributes into custom Elixir data structures during loading.

Time Complexity: O(V + E) + file I/O

Parameters

• path - File path to read from
• node_folder - Function to transform node attributes to node data
• edge_folder - Function to transform edge attributes to edge data

Returns

• {:ok, graph} on success
• {:error, reason} on file read or parse failure

Example

# Transform GraphML data to custom structs
node_folder = fn attrs ->
  %Person{
    name: Map.get(attrs, "name", "Unknown"),
    score: String.to_integer(Map.get(attrs, "score", "0"))
  }
end

edge_folder = fn attrs ->
  %Relationship{
    type: Map.get(attrs, "type", "knows"),
    strength: String.to_float(Map.get(attrs, "strength", "0.5"))
  }
end

{:ok, graph} = Yog.IO.GraphML.read_with(
  "network.graphml",
  node_folder,
  edge_folder
)

Serializes a graph to GraphML string using default attribute conversion.

Node and edge data are converted to strings and stored as "label" and "weight" attributes respectively. For custom attribute mapping, use serialize_with/3.

Time Complexity: O(V + E)

Example

iex> graph = Yog.directed()
...> |> Yog.add_node(1, "Alice")
...> |> Yog.add_node(2, "Bob")
...> |> Yog.add_edge!(from: 1, to: 2, with: "friend")
iex> xml = Yog.IO.GraphML.serialize(graph)
iex> String.contains?(xml, ~s(<node id="1">)) and String.contains?(xml, "Alice")
true

Serializes a graph to GraphML string with custom attribute mappers.

This is the main serialization function allowing you to control how node and edge data are converted to GraphML attributes.

Time Complexity: O(V + E) where V is the number of nodes and E is edges

Parameters

• node_attr - Function that converts node data to a map of attributes (node_data) -> %{string => string}
• edge_attr - Function that converts edge data to a map of attributes (edge_data) -> %{string => string}
• graph - The graph to serialize

Example

iex> graph = Yog.directed()
...> |> Yog.add_node(1, %{name: "Alice", role: "admin"})
...> |> Yog.add_node(2, %{name: "Bob", role: "user"})
...> |> Yog.add_edge!(from: 1, to: 2, with: %{since: "2024"})
iex> node_attr = fn data ->
...>   %{"label" => data.name, "role" => data.role}
...> end
iex> edge_attr = fn data ->
...>   %{"since" => data.since}
...> end
iex> xml = Yog.IO.GraphML.serialize_with(node_attr, edge_attr, graph)
iex> String.contains?(xml, "Alice") and String.contains?(xml, "admin")
true

Serializes a graph to a GraphML string with custom options.

Serializes a graph to GraphML with typed attributes for Gephi compatibility.

Identical to serialize_with/3 but explicitly intended for tools like Gephi that benefit from type information in the key definitions.

Time Complexity: O(V + E)

Example

iex> graph = Yog.directed()
...> |> Yog.add_node(1, "Node1")
...> |> Yog.add_node(2, "Node2")
iex> node_attr = fn data -> %{"label" => data} end
iex> edge_attr = fn _ -> %{} end
iex> xml = Yog.IO.GraphML.serialize_with_types(node_attr, edge_attr, graph)
iex> String.contains?(xml, ~s(attr.type="string"))
true

Serializes a graph to GraphML with typed attributes and custom options.

Provides full control over both attribute mapping and output formatting.

Time Complexity: O(V + E)

Parameters

• node_attr - Function to convert node data to attributes
• edge_attr - Function to convert edge data to attributes
• options - GraphML options tuple (see default_options/0)
• graph - The graph to serialize

Example

iex> graph = Yog.directed() |> Yog.add_node(1, "A")
iex> node_attr = fn data -> %{"label" => data} end
iex> edge_attr = fn _ -> %{} end
iex> options = {:graphml_options, 4, false}  # 4-space indent, no XML declaration
iex> xml = Yog.IO.GraphML.serialize_with_types_and_options(node_attr, edge_attr, options, graph)
iex> String.contains?(xml, "<?xml")
false

Writes a graph to a GraphML file using default attribute conversion.

This is a convenience function that combines serialize/1 with File.write/2.

Time Complexity: O(V + E) + file I/O

Parameters

• path - File path to write to
• graph - The graph to serialize

Returns

• {:ok, nil} on success
• {:error, reason} on file write failure

Example

graph = Yog.directed()
|> Yog.add_node(1, "Alice")
|> Yog.add_node(2, "Bob")
|> Yog.add_edge!(from: 1, to: 2, with: "friend")

Yog.IO.GraphML.write("network.graphml", graph)
# => {:ok, nil}

Writes a graph to a GraphML file with custom attribute mappers.

Use this when you need control over how node and edge data are converted to GraphML attributes.

Time Complexity: O(V + E) + file I/O

Parameters

• path - File path to write to
• node_attr - Function to convert node data to attributes
• edge_attr - Function to convert edge data to attributes
• graph - The graph to serialize

Returns

• {:ok, nil} on success
• {:error, reason} on file write failure

Example

graph = Yog.directed()
|> Yog.add_node(1, %{name: "Alice", score: 95})
|> Yog.add_node(2, %{name: "Bob", score: 87})

node_attr = fn data ->
  %{
    "label" => data.name,
    "score" => Integer.to_string(data.score)
  }
end
edge_attr = fn _ -> %{} end

Yog.IO.GraphML.write_with("network.graphml", node_attr, edge_attr, graph)

Writes a graph to a GraphML file with typed attributes for Gephi compatibility.

Identical to write_with/4 but explicitly intended for tools that require type annotations.

Time Complexity: O(V + E) + file I/O

Example

graph = Yog.directed() |> Yog.add_node(1, "Node1")

node_attr = fn data -> %{"label" => data} end
edge_attr = fn _ -> %{} end

Yog.IO.GraphML.write_with_types("network.graphml", node_attr, edge_attr, graph)