In this exercise, we will learn how to add attributes to the nodes of a network using the statnet package in R. Node attributes can provide additional information about the nodes in a network, such as their gender, age, or degree.
Suppose we have the network adjacency_network from 
exercise 2.11 
and we have additional information about the gender of the network members. 
We can add this information as a node attribute using the set.vertex.attribute() function:
network::set.vertex.attribute(adjacency_network, "gender", c("F", "F","M", "F", "M"))
The network:: prefix is used to specify that the function is from the network package.
We can also add the degree of each node as an attribute. 
The degree of a node is the number of edges connected to it. 
Here’s how to add the degree as an attribute called alldeg:
adjacency_network %v% "alldeg" <- sna::degree(adjacency_network)
We can check the attributes of a network using the list.vertex.attributes() function:
list.vertex.attributes(adjacency_network)
[1] "alldeg"       "gender"       "na"           "vertex.names"
We can inspect the values of an attribute in two ways. 
The first way is using the get.vertex.attribute() function:
get.vertex.attribute(net1, "gender")
"F" "F" "M" "F" "M"
The second way is using the %v% operator:
net1 %v% "alldeg"
[1] 2 4 4 1 1
        In exercise 2.1, you created the network friends_network. 
        Assume there is additional information about whether a person speaks Dutch, "D" or French, "F". 
        Person 1 and 4 speak Dutch, while person 2, 3 and 5 speak French.
        Create an additional attribute called 'language'.
    
Assume that:
friends_network, as created before, has been loaded.