d3/docs/d3-hierarchy/tree.md

Tree

Examples · The tree layout produces tidy node-link diagrams of trees using the Reingold–Tilford “tidy” algorithm, improved to run in linear time by Buchheim et al. Tidy trees are typically more compact than dendrograms.

tree()

Source · Creates a new tree layout with default settings.

tree(root)

Source · Lays out the specified root hierarchy, assigning the following properties on root and its descendants:

• node.x - the x-coordinate of the node
• node.y - the y coordinate of the node

The coordinates x and y represent an arbitrary coordinate system; for example, you can treat x as an angle and y as a radius to produce a radial layout. You may want to call root.sort before passing the hierarchy to the tree layout.

tree.size(size)

Source · If size is specified, sets this tree layout’s size to the specified two-element array of numbers [width, height] and returns this tree layout. If size is not specified, returns the current layout size, which defaults to [1, 1]. A layout size of null indicates that a node size will be used instead. The coordinates x and y represent an arbitrary coordinate system; for example, to produce a radial layout, a size of [360, radius] corresponds to a breadth of 360° and a depth of radius.

tree.nodeSize(size)

Source · If size is specified, sets this tree layout’s node size to the specified two-element array of numbers [width, height] and returns this tree layout. If size is not specified, returns the current node size, which defaults to null. A node size of null indicates that a layout size will be used instead. When a node size is specified, the root node is always positioned at ⟨0, 0⟩.

tree.separation(separation)

Source · If separation is specified, sets the separation accessor to the specified function and returns this tree layout. If separation is not specified, returns the current separation accessor, which defaults to:

function separation(a, b) {
  return a.parent == b.parent ? 1 : 2;
}

A variation that is more appropriate for radial layouts reduces the separation gap proportionally to the radius:

function separation(a, b) {
  return (a.parent == b.parent ? 1 : 2) / a.depth;
}

The separation accessor is used to separate neighboring nodes. The separation function is passed two nodes a and b, and must return the desired separation. The nodes are typically siblings, though the nodes may be more distantly related if the layout decides to place such nodes adjacent.