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From: Jack on 15 Jul 2010 19:53
Hi;
I have the following representation of a graph in a form of Adjacenct List:
0 1 2 19 20 21
1 0 3 9 10
2 0 14
3 1 4 5 6
..
..
..
which means for the first row, the node 0 is connected to node 1 and node 2..etc
I want to find all possible nodes in the graph and list them in an nx3 matrix. So for the first row the possible turns are [1 0 2; 1 0 19; 1 0 20; 1 0 21; 2 0 19; 2 0 20; 2 0 21;19 0 20; 19 0 21; 20 0 21] so the number of different turns for the first node will be (5 chose 2= 10).

Many thanks
From: Bruno Luong on 16 Jul 2010 02:41
"Jack " <jack_sama_1981(a)yahoo.com> wrote in message <i1o710$mlh$1(a)fred.mathworks.com>...
> Hi;
> I have the following representation of a graph in a form of Adjacenct List:
> 0 1 2 19 20 21
> 1 0 3 9 10
> 2 0 14
> 3 1 4 5 6
> .
> .
> .
> which means for the first row, the node 0 is connected to node 1 and node 2..etc
> I want to find all possible nodes in the graph and list them in an nx3 matrix. So for the first row the possible turns are [1 0 2; 1 0 19; 1 0 20; 1 0 21; 2 0 19; 2 0 20; 2 0 21;19 0 20; 19 0 21; 20 0 21] so the number of different turns for the first node will be (5 chose 2= 10).
>

help NCHOOSEK

Bruno
From: Jack on 16 Jul 2010 13:10
"Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message <i1ouu2$m8j$1(a)fred.mathworks.com>...
> "Jack " <jack_sama_1981(a)yahoo.com> wrote in message <i1o710$mlh$1(a)fred.mathworks.com>...
> > Hi;
> > I have the following representation of a graph in a form of Adjacenct List:
> > 0 1 2 19 20 21
> > 1 0 3 9 10
> > 2 0 14
> > 3 1 4 5 6
> > .
> > .
> > .
> > which means for the first row, the node 0 is connected to node 1 and node 2..etc
> > I want to find all possible nodes in the graph and list them in an nx3 matrix. So for the first row the possible turns are [1 0 2; 1 0 19; 1 0 20; 1 0 21; 2 0 19; 2 0 20; 2 0 21;19 0 20; 19 0 21; 20 0 21] so the number of different turns for the first node will be (5 chose 2= 10).
> >
>
> help NCHOOSEK
>
> Bruno

thanks for the advice; I used the following code but is there a faster way?
S =

0 1 2 3 4
1 0 2 4 NaN
2 0 1 3 NaN
3 0 2 4 NaN
4 0 1 3 NaN

a= size (S);
comb=[];
for i=1:a(1)
A=S(i,:)
A(1)=[];
B= nchoosek (A,2);
C=[];
C(:,1)=B(:,1);
C(:,2)=S(i,1);
C(:,3)=B(:,2);
comb=[comb;C]
end
D=[];
D=comb(:,1);
index=find(isnan(D))
comb(index,:)=[];
D=comb(:,3);
index=find(isnan(D));
comb(index,:)=[]

thanks
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