Matlab function to compute average neighbor degree

问题:

I tried searching a function for matlab that gives the average neighbor degree of a graph.

There is a function for the same in python in network-X package. So i was wondering if there's a similar function in matlab.

***********Edit****************

I cannot convert it to an adjacency matrix.. this will occupy too much of space actually.

What i have is the following edge list(Actually this is just a test matrix.. the actual one is pretty large ) as in there's an edge between node 2 to node 1 and so on.. and yes this is an un-directed graph

2 1
3 1
4 1
5 1
1 2
3 2
4 2
1 3
2 3
5 3
1 4
2 4
5 4
1 5
3 5
4 5

Now, what i need is a function that will compute the average neighbor degree(mean neighbor degree) for this graph.

回答1:

Even for large edge list, you can use Matlab to create an adjacency matrix that fits into memory using sparse matrix:

el = [2 1; 3 1; ... ]; %// edge list, I put only a tiny sample here...
n = max( el(:) ); %// number of nodes in the graph
A = sparse( el(:,1), el(:,2), 1, n, n ); % //sparse adjacency matrix

The neighbor degree of each node is the number of neighbors

nd = sum( A, 2 ); %// degree of each node

To compute the average neighbor degree, one can construct another sparse matrix with the neighbor degree stored in each entry

ndM = sparse( el(:,1), el(:,2), nd( el(:,2) ), n, n ); 

The average neighbor degree can now be computed from the new matrix

av = full( sum( ndM, 2 ) ./ nd );