In this set of exercises we shall practice the functions for network statistics, using package `igraph`

.If you don’t have package already installed, install it using the following code:

install.packages("igraph")

and load it into the session using the following code:

library("igraph")

before proceeding. You can find more info about the package and graphs in general here

Answers to the exercises are available here.

If you have different solution, feel free to post it.

A number of employees in a factory was interviewed on a question: “Do you like to work with your co-worker?”. Possible answers are 1 for *yes* and 0 for *no*. Each employee gave an answer for each other employee thus creating an adjecancy matrix. You can download the dataset from here.

**Exercise 1**

Load the data and create an unweighted directed graph from the adjecancy matrix. Name the nodes as letters A to Y. Set node color to yellow and shape to sphere. Set the edge’s color to gray and arrow size to 0.2.

**Exercise 2**

Plot the graph.

**Exercise 3**

Calculate network diameter and average closeness.

**Exercise 4**

Calculate average network betweenness.

**Exercise 5**

Calculate network density and average degree.

**Exercise 6**

Calculate network reciprocity and average transitivity.

**Exercise 7**

Calculate average eccentricity of the vertices. What is the average distance between two nodes?

**Exercise 8**

Find the hubs and plot graph with node’s size according to their hubs index. Which employee is the biggest hub?

**Exercise 9**

Find the authorities and plot graph with node’s size according to their authority index. Which employee is the biggest authority?

**Exercise 10**

Show the nodes that make diameter. Plot these nodes larger and in red. Plot edges on this path thicker in red.

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