Graph File Formats

The graph file formats include an adjacency graph format, an edge graph format, and a weighted edge graph format. All formats are ascii and entries are delimited by any consecutive sequence of delimiter characters: tab, space, line feed (ascii 0x0A), and carriage return (ascii 0x0D). Files can start and end with delimiters, which are ignored. Throughout the description n refers to the number of vertices and m to the number of edges in a graph.

Adjacency Graph

The adjacency graph format starts with a sequence of offsets one for each vertex, followed by a sequence of directed edges ordered by their source vertex. The offset for a vertex i refers to the location of the start of a contiguous block of out edges for vertex i in the sequence of edges. The block continues until the offset of the next vertex, or the end if i is the last vertex. All vertices and offsets are 0 based and represented in decimal. The specific format is as follows:

AdjacencyGraph
<n>
<m>
o0
o1
...
o(n-1)
e0
e1
...
e(m-1)

Edge Graph

The edge graph format consists of a sequence of edges/arcs each being a pair of integers. The format can either be interpreted as a directed graph or an undirected graphs depending on the application. Vertices are assumed to start at 0. The specific format is as follows:

EdgeArray
s0 t0 
s1 t1 
... 
s(n-1) t(n-1) 

where si and ti refer to the two endpoints of the undirected edge i, or the source and target of a directed edge (arc) i.

Weighted Edge Graph

The weighted edge graph format is the same as the edge graph format but includes double-precision floating-point weights. The specific format is as follows:

WeightedEdgeArray
s0 t0 w0
s1 t1 w1
... 
s(n-1) t(n-1) w(n-1)

where wi is the weight of edge i. The weight can either be in decimal or exponential notation.