How to import matrix data into NodeXL

09JanMay 7, 2015 By Marc Smith

Some network data sets are created or received in the form of a matrix.

A matrix can be directed or undirected. In this example, we will import a directed network.

First open a blank NodeXL template.

Next open the matrix workbook in the same instance of Excel (just drag it into the title bar of the current NodeXL Excel instance).

Here is a simple asymmetric matrix with weights for tie strengths.

To import this matrix, switch back to NodeXL and select the Data>Import>From Open Matrix Workbook:
2015-NodeXL-Matrix Import

A matrix may or may not have labels (row and column headers) and the user should define what their data set looks like.

The matrix may represent a directed or undirected network (if it is undirected the matrix must be symmetrical!).

This results in data appearing in the Edges worksheet of NodeXL:
2015-NodeXL-Matrix Edges

This can then be visualized as a network where the edge weights are used to set the thickness of the lines connecting two nodes:

How to plot a network in a “polar” layout using NodeXL

03MarMay 7, 2015 By Marc Smith

When a particular node in a network is of special interest it can be useful to create a network visualization in which it is located at the center of concentric rings of vertices.

NodeXL supports a “Polar” layout in which each vertex has two values that govern its location: distance from center (“Vertex Polar R”) and the angle around the clock (“Vertex Polar Angle”).

Using a random network, we added two columns to the Vertices worksheet that we called: Ring (or “Vertex Polar R”) and Rotation (or “Vertex Polar Angle”). We then assigned values for the “Ring” and the “Rotation” for each Vertex:

These values can then be mapped to the location for each Vertex using the NodeXL Autofill columns feature:

When these values are applied to the network visualization and the layout is set to “Polar” the visualization repositions each vertex into a position around a ring. The values are set by mapping Vertex Polar R to “Ring” and Vertex Polar Angle to “Rotation” and then selecting “Autofill”. The result is a single ring plotted around a core:

To see this more clearly, I built a larger random network with 100 vertices and added two more “rings”. The resulting image looks like this:

How to schedule the creation of a network with NodeXL and Windows Task Scheduler

23AugMay 7, 2015 By Marc Smith

NodeXL has a number of data importers that can create a network of connections from social media data sources like Twitter, YouTube, flickr, email, and the WWW (along with a number of other data import formats like GraphML, UCINet, CSV, and other Excel workbooks with data).

To create a network you just select the search terms and configurations you want from the NodeXL>Data>Import menu.

If you want to create the same network every day (or at any schedule), a recent feature (since version .125) of NodeXL can help. NodeXLNetworkServer.exe is an application that ships with NodeXL along with a sample configuration file called SampleNetworkConfiguration.xml. By editing the configuration file you can set NodeXL to collect anything available in the menu through Excel. So far we have exposed the two Twitter data collectors (more on the way) so the configuration file asks you to select a search term or a user’s name, the size of the network and the details you want reported along with the location and name of the destination file that NodeXL will create. Answer these questions by editing the config file and save it with a useful name that includes the search term.

Step by step details after the jump:

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