The simplest way to visualize an adjacency matrix is to plot the matrix as a table, using colors or other highlighting techniques to emphasize the weight of each connection, producing a heatmap visualization. This can be easily done with HTML tables, but SVG offers more flexibility and interactive resources. D3 does not, however, provide a layout generator function in D3 to plot adjacency heatmaps, but it's not difficult to create one.
As an example, consider the following CSV data (see Data/sa_borders.csv) containing a triangular adjacency matrix, where each element represents the border between two South American countries or its coastline with the Atlantic or Pacific oceans:
Country,Atlantic,Pacific,Brazil,French Guyana,Suriname,Guyana,Venezuela,↵
Colombia,Ecuador,Peru,Bolivia,Chile,Argentina,Uruguay,Paraguay
Atlantic,0,0,,,,,,,,,,...
