This example shows a force-directed network graph of 28 nodes and 29 directed links, where each link’s opacity encodes the numeric value from `force.csv`. Thicker, more opaque edges (e.g., value 2.0 between Eveie and Harry) indicate stronger connections, while fainter edges (e.g., 0.1 between Harry and Eveie) represent weaker ties. The graph uses `d3.layout.force` for the physics simulation and animates node positions in an SVG via a `tick` handler that draws curved paths with arrowheads. Interactivity is limited to click and double-click events, which enlarge and highlight individual nodes and their labels. The code derives opacity classes from a linear scale mapping link values to 25%, 50%, 75%, or 100% opacity.