Plain-text formats for graph structures

DOT format

Summary:

• the graph should have a string value for a name
• data are organized with one line per edge
• each line is formatted as two nodes joined by ` – `
• edges may optionally be weighted by assigned a weight value in brackets

Example:

graph "GRAPHNAME" {
	"name1" -- "name2" [weight = 5]
	"name1" -- "name3" [weight = 1]
}

GML format

Summary:

• The graph should have an ID string and label
• each node is listed with an ID number, label and any other attributes you want
• each edge is listed with a source node and target node identified by their ID numbers, and any other attributes you want

Example:

graph [
	comment "Hand-crafted example of co-occurrence network"
	directed 0
	id socialnetdemo
	label "Example list of personal names"
	node [
		id 1
		label "Patroclus"
		count 1
	]
	node [
		id 2
		label "Sarpedon"
		count 1
	]
    edge [
		source 1
		target 2
		weight 4
	]
]

Comparison of some key features

Format	Supports weights on edges	Supports counts on nodes	Distinguishes node IDs from labels
DOT	✅	❌	❌
GML	✅	✅	✅

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