Treemap 4.1 Documentation


[Previous]   [Table of Contents]   [Next]

Network Visualization (NetViz)

NetViz is the abbreviation for Network Visualization and this abbreviation is commonly used in Treemap. This feature allows to have links between leaf nodes. Those links are stored in a .tnv file (stands for treemap netviz file). The format of tnv files are defined below.

The NetViz feature is special in that there are no arrows to indicate incoming and outgoing links. Instead, the curvature of the link is used to determine that. The curve is nearer to the source node.

A .tnv file depends on leaf nodes that Treemap shows just before loading it (the .tnv file). Steps to visualize the links are as follows:
(Suppose our data input file is a .tm3 file.)

  1. Make sure you have a .tm3 file and a corresponding .tnv file.
  2. Open the .tm3 file.
  3. Select File->Import NetViz Table from the menu.
  4. Open the .tnv file that corresponds to this .tm3 file.
  5. Under Options menu either choose Enable global Netviz feature to view all links or Enable under cursor NetViz feature to view the links that are related to one node at a time. Position the mouse over a node and you will see all incoming and outgoing links of that node.

Color of links

The color of all links are RED by default. If you want to base the color of a link on a nominal attribute of the target node, go to the Legend Tab in Control Panel and choose the attribute you want to be effective from the "Link Color" combo box.
This combo box will appear only when necessary, that is whenever a .tnv file is loaded or whenever a directory is mapped during which automatic generation of NetViz links is requested. When you load a new file, since there will be no NetViz links associated, the combo box will disappear.

The format of .tnv files

.tnv files are TAB delimited text files that can be opened by or generated in Excel.

For an input data file to have a corresponding .tnv file (or .tnv files), the input data must have an attribute that has a unique value for every node. We call an attribute having this property a key attribute. If you create a key attribute, it is strongly recommended that you choose its type as STRING.

The first line of a .tnv file has the name of a key attribute, which should appear exactly the same as in the data input file. Every other line in the file represents the links as follows: The first column of every line has the source node's key attribute value and the remaining columns have the target nodes' that the source node connects to.

Name
A B D E
C A B
.tnv file example
In this example, the name of the key attribute is "Name". A has outgoing links to B, D and E; while C has outgoing links to A and B.

Automatic Generation of NetViz Links As Mapping a directory

When mapping a directory, you have the choice of automatically generating NetViz links. (See Directory Mapping to learn where this choice appears.) All .html, .shtml, .htm files (case of extension doesn't matter) will be examined for HREF and SRC tags and as long as the references can be found under the directory that is mapped, NetViz links will be generated from those files to the nodes representing references.

After mapping a directory to generate NetViz links, it is a good idea to go to the Legend Tab (in Control Panel) and set the "Size" legend to "NONE". This setting leads to a clearer appearance of NetViz links.

Questions

Contact us at: treemap@cs.umd.edu
Return to Treemap main page