Overview

.NetMap is a pair of applications for viewing network graphs, along with a set of .NET Framework 2.0 class libraries that can be used to add network graphs to custom applications.

A network graph is a series of vertices (sometimes called nodes) connected by edges. See this Wikipedia article for an overview of network graphs.

.NetMap was created by Marc Smith's team at Microsoft Research.

Here is a sample network graph created by .NetMap. It shows an individual's network of friends within Facebook.com:



Here are some other .NetMap graphs:

.NetMap Excel 2007 Template

The easiest way to use .NetMap is to install the .NetMap Excel 2007 Template. With the template installed, you can enter network data into a template-based Excel 2007 workbook, then view the network graph within the workbook's window:



A simple two-column edge list is all that is required by the template, but a variety of optional columns can be used to customize the graph's appearance. These include edge color, width, and opacity; and vertex color, shape, radius, opacity, label, tooltip, and location. In this example, a few of the optional columns have been used to customize the previous graph:



Because you enter graph data in a familiar Excel workbook format, there is no need to learn a complex, arcane file format to display your graph. And because Excel 2007 is used as an application platform, the full power of Excel is available for filtering and computing vertex and edge data.

Layout Algorithms

By default, the Fruchterman-Reingold layout algorithm is used to lay out the graph's vertices, but a variety of additional layout algorithms are provided as well. You can repeatedly lay out either all of the graph's vertices or just a selected subset.

Graph Metrics

A number of graph metrics can be computed and inserted into the Excel 2007 workbook on demand, including vertex degree, betweenness centrality, and clustering coefficient. The graph metric framework is extensible and other metrics will likely be added in future releases.

Email Analysis

If you use Outlook, Outlook Express, Windows Mail, or a similar email client, and if you have Windows Desktop Search installed on your computer (it comes with Vista and can be installed separately on Windows XP), you can use the Excel 2007 template's "Analyze Email Network" Ribbon command to graph the network of people you communicate with via email.

Standalone Desktop Application

In addition to the Excel 2007 template, the source code includes a standalone desktop application for viewing network graphs. The application reads graph data from either a Pajek file or a simple edge-list text file. The degree of graph customization is much more limited in the desktop application than with the Excel 2007 template.

Class Libraries

The Excel 2007 template and the desktop application display graphs using a custom Windows Forms control that can also be used in other applications. In fact, the template is just a Visual Studio Tools for Office 3.0 wrapper around a stack of reusable, prebuilt class libraries.

The Windows Forms control is one of several graph "visualizers" that are packaged in a Microsoft.NetMap.Visualization assembly. There is also a Microsoft.NetMap.Adapters assembly for reading and writing graph data in various formats, a Microsoft.SocialNetworkLib assembly for analyzing social networks, and a Microsoft.NetMap.Core assembly that implements the low-level vertex, edge, and graph classes. The framework for a Microsoft.NetMap.Algorithms assembly is also provided, although most of the graph algorithms are still work items as of May 2008.

The class libraries are documented in a help file created with NDoc. Search for the NetMapApi.chm file in the class libraries.

Important Note: You may see nothing but empty topics when you attempt to view the NetMapApi.chm file. To fix this problem, which is due to a security restriction in Internet Explorer 7, right-click the chm file in Windows Explorer and click the "Unblock" button on the General tab.