The `'connectionRatio'` link anchor function places the anchor of the link at a point at a specified ratio of the reference link's length (from reference link's source). It accepts one argument, which can be passed within the `linkAnchor.args` property:

ratio | number | The length ratio of the target anchor. Default is `0.5`, meaning the midpoint of the reference link.

Example:

    link.source(link2, {
        linkAnchor: {
            name: 'connectionRatio',
            args: {
                ratio: 0.25
            }
        }
    });