Chapter 5. Tutorials

Chapter 5. Tutorials
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Table of Contents

1. First Step

Displaying your first graph
Saving
Algorithms

2. Improving a layout

Introduction
File system import
Using other Layouts
Showing Labels
Showing a specific kind of file.
Conclusion

3. People in InfoVis

Analyzing an author
What, if any, are the relationships between two or more or all researchers

1. First Step

The goal of this part is to make a graph and to save your work.

Displaying your first graph

Importing a graph

Select the File->Import item.
Select an import method. For instance, Grid approximation.

Accept with the default parameters. A graph with nodes and edges is now displayed. With the mouse wheel, you can zoom on the graph to see a specific node. By moving the mouse with the left button pressed, you can translate the graph in the plane of the view. Pressing the SHIFT key allows to rotate the graph, and the Ctrl key (Alt on Mac) allows to rotate around the z axis and zoom. In order to come back to the first and default point of view, Select View->Center view from the contextual menu.

Select Algorithm->Measure->Misc->Id from the menu, to compute a value (metric) for each node and edge of the graph.

The graph is now displayed with colors depending on the metric. You can change the colors with the menu : Algorithm->Color->Metric Mapping. This plug-in allows you to choose any number of colors, and computes an interpolation to fill in the blanks if needed (or you can force colors to some values by using the enumerated mode).

Creation of a graph

In this section, we will learn how to create a new graph, element by element.

Select File->New from the menu to create a new graph.
Create a graph by adding nodes and edges. To add a node, select the tool and click Where you want to add a node. To add an edge, select the tool. Click on the source node, then on the target node. You can control whether to display or hide edges with the Edges visibility checkbox in the Layer Manager tab, located in the View Editor tab, in the left-hand dock. Visibility checkboxes are in the first column, the second column contains stencil checkboxes (When one layer has the stencil, it is displayed on top of layers who do not have it). There are several other checkboxes here, most notable are options to display or not nodes, node labels and edge labels. In the same way, you can display or hide the arrows indicating the edge direction in the Rendering Parameters tab, by checking the Arrows checkbox in the Edges section.
To delete elements of the graph. Select the tool, then click on the element you want to delete.

Saving

To save your work, you just have to select File->Save or File->Save as. A dialog will appear allowing to enter the author of the graph and some comments; then after clicking on the 'OK' button, type the file name and choose its location.

The second way to save is to export the graph in one of the formats Tulip supports. By default, only GML and TLP exports are installed. To install more, look at the Plug-ins Management section of this help. Select File->Export and the format of your choice, then choose the file name and location.

Algorithms

This part explains how to apply an algorithm to a graph. You need an open graph to apply an algorithm on (you can create or import one). All the algorithms you can apply on graphs are located in the Algorithm menu. There are Layout algorithms, Measures, Selection, Clustering (in General) and more ! For instance, select a layout algorithm by navigating to Algorithm->Layout, and then select Hierarchical->Hierarchical Graph.

this algorithm deals with the layout of the nodes and the edges. Some layout algorithms may not apply to your graph if it does not belong to the right category of graphs. Trying to apply the Bubble Tree to a grid is not possible, as this algorithms needs a tree-like graph to be applied. In these cases, a pop-up message will display an explanation of the problem.