Collections (tutorial)

A network collection is a set or sequence of several networks that belong together, e.g., by building a longitudinal network (i.e., a network observed at several moments in time). Network collections can be jointly analyzed and visualized (e.g., computing the same centrality index or applying the same layout algorithm on all open networks). A visone network collection that represents longitudinal data can be visualized by a dynamic layout algorithm showing the evolution of the network over time and it can be analyzed with the RSiena software for modeling the co-evolution of networks and behavior. This trail guides you through these application scenarios in an example-driven way. To follow the steps illustrated here, download the file Newfrat_top3.zip, linked from and described in the page Newcomb Fraternity (data), and extract (unzip) its content (consisting of the files newfrat01.graphml to newfrat15.graphml) to your hard disk. This trail assumes that you have basic knowledge about working with visone as it is illustrated in the other three basic trails.

Dealing with several networks (basics)

In visone, several networks can be open at the same time - each in its own network tab. In general, you can load networks into visone by (1) starting a new empty network, (2) by opening a network from a local file, or (3) by creating a random network. To load the set of networks that serves as illustrating example in this trail, click on the menu file, open, navigate in the file browser to the directory where you've put the files newfrat01.graphml to newfrat15.graphml (see above) and select all of them before you click the ok button. (Selection of these files can be done in different ways, for instance, by keeping the Control-key pushed while successively selecting the files with a mouse left-click or by clicking on one of the files and then keeping the Control-key pushed while typing a to select all files in the current directory.)

The 15 networks should be shown in 15 separate tabs in the network area. To switch between these networks, click on the name of the respective network on top of the tabs (there are little buttons with left/right-arrows on the right-hand side in the row of network names that allow you to browse through the tabs when the list of names exceeds the screen width). To close a tab, click on the X-like cross on the right-hand side of the respective tab. To close all tabs or all tabs but the current one, do a mouse right-click on one of the network names and select the appropriate option; if there are unsaved changes, visone asks you whether you want to save the files and you can answer yes/no separately for each network (click the yes or no button, respectively) or chose to quit without saving any changes (no to all) saving all modified networks (yes to all) or chose cancel, that is not to close the tabs. (If you closed one or several of the networks, remember to open them again to follow the steps below.)

Simultaneous analysis and visualization

Network analysis and visualization algorithms can be applied to all open networks simultaneously. For instance, to compute the indegree of nodes in all 15 networks that are currently open in visone go to the analysis tab, make the appropriate choices to compute indegree (for information on this see the trail on visualization and analysis), and select open networks in the apply to drop-down menu at the bottom of the analysis tab before pushing the analyze! button. Each of the networks has now an attribute called indegree (or whatever name you've chosen) whose values are equal to the nodes' indegrees at the respective time points.

Applying a visualization algorithm simultaneously to all open networks works accordingly. For sake of example, map the newly computed indegree to the node size (more information about how to map attributes to graphics can be found in the trail on visualization and analysis).

Creating a network collection

The analysis and visualization algorithms illustrated processed the networks separately, one at a time. So far, a node in one network has not been identified with any node in another network. To do this you have to tell visone which attribute is the one that identifies nodes. This is done by creating a network collection with the collection manager.