How deeply does D3.js in Action, Third Edition cover strength accessor?

Explains the default value and directional results of weakening positioning forces, without detailing force calculations.

Strength accessor in D3.js in Action, Third Edition

A strength accessor specifies the magnitude with which a D3 force influences nodes or links.

The D3 strength() accessor controls how strongly a force pulls or pushes nodes in a force simulation. Positioning forces default to strength 1; lowering one makes its influence weaker relative to the others. section 12.4.1

For example, combine forceX(0) and forceY(0), then reduce the x-force strength to 0.01. Nodes are drawn toward the center much more strongly vertically, so they remain loosely spread along the x-axis. Lower the y-force instead to reverse the effect. strength() works with any D3 force. section 12.4.1

Use strength() to tune a layout’s visible behavior:

Balance horizontal and vertical attraction to loosen a layout along one axis. section 12.4.1
Adjust positioning forces while combining them with collision force to form layouts such as beeswarm charts. section 12.4.1
Assign scale-derived target positions to positioning forces when creating distinct clusters. section 12.4.1

Figure 12.12 We can control the strength with which a force is applied with the `strength()` accessor function. By default, this strength is set to `1`. If we apply both an x-force and a y-force but weaken the x-force, the attraction toward the coordinate (0,0) will be stronger vertically than horizontally. If we do the reverse, the attraction toward the center will be stronger horizontally than vertically.

Compare weakened x- and y-forces to see how relative strength changes the direction in which nodes stay most tightly grouped. section 12.4.1

How D3.js in Action, Third Edition covers it

This explainer was generated by Manning's knowledge graph from the text of D3.js in Action, Third Edition. The section links point to the parts of the book it draws on.