Have any API to make some nodes to do tree-layout in normal layout?

I want to select some nodes and make them tree-layout.
Have any API to do that?
Or I need to implement it myself

The literal answer to your question is:

myDiagram.layout.doLayout(myDiagram.selection)

But I think you would want to include all links between the selected nodes, even if the links were not selected. So I would initialize a Set with the selected Parts and then add any unselected Links that connect two Nodes that are selected.

Thank you,
I mean that the diagram’s layout isn’t “go.TreeLayout”,but i want to make some nodes tree-layout.
This is my solution,is there a better way?

function makeTreeLayout() {
  const diagram = getDiagram()
  if (diagram.selection) {
    const tempLayout = diagram.layout
    // make is go.GraphObject.make
    diagram.layout = make(go.TreeLayout, { angle: 90, arrangement: go.TreeLayout.ArrangementFixedRoots })

    diagram.layout.doLayout(diagram.selection)

    diagram.layout = tempLayout
  }
}

Don’t set Diagram.layout.

The Mind Map sample, Mind Map, does what I think you want. Look at the context menu command and various calls to layoutAngle.