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Visualizing and Editing Graphs

Revision as of 09:25, 27 January 2012 by Christian.thoens.gmail.com (Talk | contribs) (Visualizing and Editing Graphs)

Visualizing and Editing Graphs

STEM uses graphs as data structure to save information concerning population sizes, areas, spatial information, neighborhood of areas etc. When you start a scenario, you get the information of its appendent graphs in a visual form, e.g. when you see the outlines of the countries you included into you scenario. The Graph Editor offers the possibility to visualize graphs without starting a scenario. You can get a view of the data, edit titles, area sizes, add populations and adjust geographic information of a node. It also possible to create edges between existing nodes.

Step 1. Open the Editor

When you right-click on an item of the type "Model" within a project of the STEM Explorer, you'll see a context-menu that offers you to display the canonical graph of all graphs that are contained in this model. In order to display a single graph you have to add it to an empty model.

Step 2. Editing the graph

The nodes of the graph are small circles, where the color shows the membership to one subgraph, i.e. when you have opened a canonical graph consisting of several countries, the country nodes will have different colors. When you click on a node (provided the graph contains nodes with spatial information, otherwise nothing will be shown in the display) you get information about its title, its URI and all labels that are assigned to this node. You can move the nodes by keeping the left mouse button pressed and drag the node to your desired location. When you want to add a label to a node (e.g. add information about population size or area of the node) you must select one node by left-clicking on it and open the context menu with a right click. You can then add a population or area label and edit the values in the bottom part of the editor.

Edges can also be selected. Information about the class of edge and potential edge values are shown in the bottom part of the display.

You can zoom in and out with the mouse wheel.

Step 3. Saving the graph

When you want to save the edits you have made, you can select "Save" (and the changes are saved into the same files) or you select "Save As" where you have to select a folder and filename. When you were working on a reference to graphs in the STEM graph/model repository, local copies of the references including your changes will be saved to your workspace. If you were working on local copies already, your files will be overwritten, when you select "Save Graph".