Connected components in a graph

M=[1 2;2 5;3 4;4 6;6 7;6 8;6 9;6 10];
G=graph(M(:,1),M(:,2))
[bins,binsizes]=conncomp(G);

When I use the built in function conncomp, MATLAB always assumes that first component of graph G is the one which node 1 belongs to.

The output bins in the given example is:

bins=[1 1 2 2 1 2 2 2 2 2] How can I make the first component of my graph is where node 6 (for example) belongs to?

Your help would be appreciated.

Thanks!

Answer 1

[Matt J]

M=[1 2;2 5;3 4;4 6;6 7;6 8;6 9;6 10];
G=graph(M(:,1),M(:,2));
[bins,binsizes]=conncomp(G);

idx=[2,1];

binsizes=binsizes(idx);
bins=idx(bins)

bins = 1×10

2 2 1 1 2 1 1 1 1 1

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[Asaf McRock]

Thank you very much, Matt!

This is so clever. But I wonder if it works for higher number of components.

Could your trick be generalized? I'm new to programming, so excuse my ignorance.

[Matt J]

You would just need to change idx to an appropriate permutation of 1:N, e.g.,

idx=[3,1,2,4]

[Asaf McRock]

Awesome, got it.

Thank you again.