Compare function in treelayout

zubinshi · September 30, 2014, 2:12pm

Hi,

I am trying to define custom compare function in treeLayout. here is the sample code, i am using:

var treeLayout = new go.TreeLayout();
 treeLayout.angle = 90;
 treeLayout.comparer = treeNodeComparer;
 treeLayout.sorting = go.TreeLayout.SortingAscending;
 treeLayout.path = go.TreeLayout.PathSource;

function treeNodeComparer(first,second)
 {
 var firstNode= first.node.data;
 var secondNode=second.node.data;

 if (first.topNode)
 return 1;
 if (second.topNode)
 return -1;
 return 0;
 }

The issue i am facing is that if i set treeLayout.path to something beside TreeLayout.PathSource, the custom comparer function will not used to re-sorting. Even with TreeLayout.PathSource it only compare partial nodes instead of All.

Basically what i want to do here is: to set particular node on top all the time and particular node on the bottom of tree. and all other nodes are following by some logic.

Thanks,

walter · September 30, 2014, 4:26pm

The TreeLayout.sorting and .comparer properties govern the order of the (multiple) children of a parent vertex.Â It is not used to determine what “layer” the vertex/node should be in.

Root nodes/vertexes are automatically determined to be those that have no links/edges coming in.Â Or if Diagram.isTreePathToChildren is false or if TreeLayout.path is TreeLayout.PathSource, those with no links/edges going out.

zubinshi · October 1, 2014, 9:58am

thanks for the information. Is there a work around to do that right now? or is there a plan to add such feature in next version?

Thanks,

walter · October 1, 2014, 11:58am

I don’t know what you are looking to do. Are you trying to put the root node in some level/layer other than the first one? If so, I don’t know how well the TreeLayout will work.

If you are trying to put leaf nodes/vertexes, or whole subtrees, at levels/layers that are deeper in the tree than they would normally be, I think that could be done. In fact, that is exactly what the Parse Tree sample does: Parse Tree

zubinshi · October 1, 2014, 2:39pm

what I am trying to do here is to specify a node to be root of tree no matter where it original position is. for example, I have a tree with nodes a, b, c, d, e and with link looks like:

links:[
{
 {“from”:a,“to”:b},
 {“from”:a,“to”:c},
 {“from”:c,“to”:d},
 {“from”:b,“to”:e},
}
]

With above data, A will be root and shows on top of tree. but i want to do here is to show b on top of all.

I will take a look on parseTree.

walter · October 1, 2014, 3:02pm

Well, you could reverse the TreeEdge that runs from “a” to “b”. I think that would give you the effect that you want (i.e. “b” on top) without messing up the laid-out positions of any other nodes. And doing so in an override of TreeLayout.makeNetwork means that you would not actually be modifying or replacing any Links in the Diagram.