CS 790g Seminar: Complex Networks
Network Lab 1
Due on Thursday Sep 2, 2010 at 1:00 pm
Network Basics (3 points)
Go to the site http://www.visualcomplexity.com.
Select and list two projects describing a network.
Answer the following about them (this may require going into the source webpage for the project, linked to from the visualcomplexity site).
- What do the nodes and edges represent?
- Is the graph directed? Weighted?
- Can the data be represented as a bipartite graph?
Bipartite Graphs (7 points)
For this part, you may look at Pajek tutorial.
- Download the file actorsandmovies.net
- Open it in Pajek by either clicking on the yellow folder icon under the word "Network" or by selecting File>Network>Read from the main menu panel.
- A report window should pop up confirming that the graph has been read and the filename and location will be displayed in the 'active' position of the network dropdown list.
- This is a 2 mode network containing two classes of nodes, actors and movies. Create a 2-mode partition (Net>Partition>2-Mode).
- Visualize the network using Pajek's Draw>Draw-Partition command from the main menu panel. The two classes of nodes should be colored differently.
- If labels are not shown, add them (Options>Mark Vertices Using>Labels).
Submitting your files
- Select from the draw toolbar a layout algorithm under 'Layout>'. Apply your favorite layout algorithm. Include an image.
- Transfrom the network into a one-mode network (Net>Transform>2-Mode to 1-Mode>Rows). Draw the network (Draw>Draw). Include an image.
- Qualitatively compare the structure of the 2-Mode to the 1-Mode network. Is there a loss of information?
- Show the weights on each edge using (Options>Lines>Mark Lines>with Values). What do the values represent?
- Compute the unweighted degree of each node (Net>Partitions>Degree>All). Next draw the network using (Draw>Draw-vector). How is the degree represented?
- Add the vector value to each vertex (it will be the degree/(max possible degree)) (Options>Mark Vertices Using>Vector Values). Include an image.
- Who are the most important actors using this measure?
- How does the boundary of the network (i.e. who is included) affect who is found to be most central?
- Load the file actorsandmoviesWithGere.net. It contains one extra actor, Richard Gere. Repeat the above procedure.
- In the 1-mode network of actors, is there a change in who is most central?
- What does this tell you about biases and boundaries in sample selection?
- Remove all edges between actors who have costarred in fewer than 3 movies (Net>Transform>Remove>Lines with value>Lower than). Which actors comprise the central core of this network?
Submission of your homework is via WebCT.
You must submit all the required files in a single document containing all the answers.
Acknowledgement: The assignment is modified from Lada Adamic.