clc;
clear;
fileID = fopen('karate.adj','r');
row = split(strtrim(fgetl(fileID)));
n = size(row,1);
frewind(fileID);

ii = [];
jj = [];
vv = [];

for i = 1:n
    row = split(strtrim(fgetl(fileID)));
    for j = 1:n
        num = str2double(row(j));
        if num ~= 0
            ii(end+1) = i;
            jj(end+1) = j;
            vv(end+1) = num;
        end
    end
end
fclose(fileID);

A = sparse(ii,jj,vv,n,n);
names = string(1:n);

disp("Exercise 6.1:");
degcentrality(names,A);

disp("Exercise 6.2:");
pagerank(names,A);

disp("Exercise 6.4:");
x = randperm(n);
gs = 450;

%group1 = [1 2 3 4 5 6 7 8 11 12 13 14 17 18 20 22];
%group2 = [9 10 15 16 19 21 23:34];

deg = sum(A);
L = full(diag(deg) - A);
[V, D] = eig(L);
fprintf("lambda_2: %d\n", D(2,2));
[sv, p] = sort(V(:,2));
figure;
plot(sv, '.-');
%matlab2tikz('../ex6_6_ev.tex');
figure;
subplot(1,2,1)
spy(A);
subplot(1,2,2)
spy(A(p,p));
%matlab2tikz('../ex6_6_spy.tex');
fprintf("Group 1: ");
display(sort(p(1:16))');
fprintf("Group 2: ");
display(sort(p(17:end))');