Graph data can be represented in different formats for onward computation. The choice of the graph representation hugely relies on the density of the graph, space required, speed and weight of edges. The main ways a graph can be represented are as an adjacency matrix, incidence matrix, adjacency list and incidence list.

Adjacency Matrix: This is one of the most popular ways a graph is represented. One of the core aims of this matrix is to assess if the pairs of vertices in a given graph are adjacent or not. In an adjacency matrix, row and columns represent vertices. The row sum equals the degree of the vertex that the row represents. It is advisable to use the adjacency matrix for weighted edges.  You replace the standard ‘1’ with the respective weight.  It is easier to represent directed graphs with edge weights through an adjacency matrix. Adjacency matrix works best with dense graphs. As dense graphs usually have twice the size of the edges to the given nodes.

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