The next step is to begin creating your legend. How you create the legend depends on the values for attributes of the nodes and edges in your network. This is the information you want to convey to those who see your visualization. In the following steps we will be working with the co-author network we generated from the FourNetSciResearchersflorentine.isi nwb file in section 184.108.40.206 Author Co-Occurrence (Co-Author) Network section 2.7 Visualizing Data with Sci2 on the Sci2 wiki . As you may remember, the nodes have been sized based on the wealth of the family represented by the node and colorized based on the number of publications priorates a particular author has in this data setfamily held. The edges have been sized and colorized based on the number of co-authored works in this data settype of relationship that connects two families: business tie or marriage. So, based on these attributes we are going to create titles and subtitles for our legend:
With this toolbar you can change the font and size of the text, as well as other attributes. If you want to change the color of the text you can do so by using the color pallet at the bottom of the tool:
220.127.116.11 Creating Legend Symbols
In order to determine the values for our symbols we will need to refer back to the original visualization. In GUESS you can use the information window to view these values. Simply hover your mouse over the node or edge you wish to examine and view its properties in the information window:
To find the values for attributes of nodes and edges in Gephi, view the graph in the Overview window of Gephi. Then use thetool and label the edges and the nodes:
Once you have chosen which attribute to label the nodes or edges with they can be applied by clicking the label tool:. It is a good idea to label nodes and edges separately. In other words, apply the node labels and then remove them before you apply the edge labels. Otherwise, the graph will be too crowed with node and edge labels to identify values to use in your legend. Typically, it can be difficult to identify edge attribute values because there are so many edges to be labeled that it can become crowded very quickly. One trick when dealing with a lot of attribute labels is to use the Gephi filters to filter either nodes or edges by certain attributes. To pull up the filter window in Gephi go to "Window > Filters" at the top of the tool:
The filter window will appear at the right-hand side of the tool. You can choose to filter edges by the edge weight (number of co-authored papers) attribute by dragging the edge weight filter into the queries section below:
Use the slide bar at the very bottom of the window to filter the edges. Drag the bar and then click filter:
To create the symbols in the legend, we will be using differently sized circles (representing nodes) to convey the number of papers and differently weighted lines (representing edges) to convey number of times co-authoredwealth of the families in this network.
First, find the author family (node) with the highest number of publicationsmost wealth. In the case of this co-author network it is Albert Barabasi, with 127 papersthe Strozi family with 146 thousand lira. The Barabasi Strozi node will serve as the highest point on the scale. Next, find an author with one publication, the smallest node, or the least wealthy family, to serve as the lowest point of the scale. One of the smallest nodes on the graph will sufficeIn this case it is the Pucci family with 3 thousand lira. Finally, you will need to find a node to serve as the middle point on the scale. In the case of this network we will use Stefano Zapperi, with 33 publicationsthe Barbadori family with 55 thousand lira.
Once you have identified these nodes you can select them in the Inkscape file:
It is helpful to zoom in on the image and make sure you are actually selecting the border around the node. Once you have made the selection, copy the selection by right-clicking and copying the selection (or by using the Ctrl+C keyboard shortcut). Then paste the copy below the first title "Nodes Size & Color."
Repeat these steps for the edges. Identify the edge between the authors who have co-authored the most, in this case the edge between Barabasi and Zapperi. Next find an for the lowest limit on the scale, a pair of authors who have co-authored once Finally, identify an edge somewhere in the middle, in this case the edge between Barthelemy and Barrat. When you select the edges, it is best to zoom in on the graph and use the selection tool to click directly on the edge:
Once the desired selection has been made, copy the edge by right-clicking and copying the edge (or by using the Ctrl+C keyboard shortcut). Then paste the selection below the "Edge Size & Color" title. You will notice that when you copy the edge, it will retain the angle at which it is displayed in the graph. With the selection tool: double-click on the the edge. This will allow you to manipulate the angle of the edge by clicking and dragging:
Zooming in on the edge will help you make sure you have the angle of the edge as close to 180 degrees as possible. Repeat these steps for the other two edges. When the you have created the symbols for the three edges and the symbols for the
If you are unable to accurately copy and past the circles from the network you can create your own using the circle tool and manually creating the symbols:
When the you have created the symbols for thee nodes you may need to change the stroke and fill colors so that all the symbols are the same. To change the stroke color and the fill color for any object in the graph simply use the selection tool: to identify the object and then go to "Object > Fill and Stroke..." in the tool menu. This will bring up the pallet you need to edit the fill and stroke for objects:
This tool will allow you to edit the RGB values for both the stroke color and the fill color of objects. Once you have all the symbols created and uniformly colored it should look something like this:
The next step will be to create a gradient scale for the color of both of the nodes and the edges. Using the rectangle tool: create a rectangle below the node symbols and copy it below the edge symbols:
Now we need to fill each rectangle with the range of colors we applied to the nodes and the range of colors we applied to the edges, respectively. Select the first rectangle, under the Node Size & Color title. You will notice that in the fill tab there is the option to fill an object using a linear gradient:
Then use the eyedropper tool: any of the smallest grey nodes on the graph will workthe Pucci family node. Repeat this process, select the circle at the right-side of the blue line and use the eyedropper tool to select the color from the largest node. Follow these steps for the next rectangle, under the Edge Size & Color title. For the color at the left-end of this spectrum, use one of the thinnest edges, and for the right-end of this spectrum, use black from the thickest edge:and select the color from a node at the lowest limit of the scale,
The last step is to add the values to each of the components using the text tool:
the Strozi family:
The next step is to create two symbols below the "Edge Color" title to represent the two types of relationships in this network. Use the rectangle tool to create the symbols:
Now you have created a legend for this visualization! A person who sees your visualization will now be better able to understand exactly what information is meant to be conveyed with this visualization. Feel free to think of other ways to convey the information about the various attributes of you visualization.