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matlabmatrixoctave
gorgi93
gorgi93

Reputation: 2535

Matlab how to bitwise-AND of a vector and a matrix?

I want to find out the index of the matrix column in which the vector appears. My idea is to do AND of the vector over matrix and only the column that is the same will be 1 in the new vecotr. But I don't know how to do this. Below is example:

H =
0   0   0   0   1   1   1   1   1   1   1   1   0   0   0
0   1   1   1   0   0   0   1   1   1   1   0   1   0   0
1   0   1   1   0   1   1   0   0   1   1   0   0   1   0
1   1   0   1   1   0   1   0   1   0   1   0   0   0   1

S =
0   1   0   1

From that I want to get 2 as second column or even better vector 

0 1 0 0 0 0 ... 0

Since there is error in second column.

How can I do this in Matlab or even better Octave?

Upvotes: 2

Views: 254

Answers (4)

gorgi93
gorgi93

Reputation: 2535

I found out the function

ismember(H', S, "rows")

works exactly as I want. Your answers are all good too, thanks.

Upvotes: 2

carandraug
carandraug

Reputation: 13081

That's pretty easy with broadcasting. The following will require Octave 3.6.0 or later but you can use bsxfun if you have a previous version:

octave-cli-3.8.1> h = logical ([
0   0   0   0   1   1   1   1   1   1   1   1   0   0   0
0   1   1   1   0   0   0   1   1   1   1   0   1   0   0
1   0   1   1   0   1   1   0   0   1   1   0   0   1   0
1   1   0   1   1   0   1   0   1   0   1   0   0   0   1]);
octave-cli-3.8.1> s = logical ([0   1   0   1]');
octave-cli-3.8.1> all (h == s)
ans =

   0   1   0   0   0   0   0   0   0   0   0   0   0   0   0

From here, it's all a matter of using find to get the column numbers. It will even work if it matches more than 1 column:

octave-cli-3.8.1> find (all (h == s))
ans =  2

Upvotes: 1

Dennis Jaheruddin
Dennis Jaheruddin

Reputation: 21563

Not really sure how you tried to approach the problem. But with repmat or bsxfun it is as simple as this:

all(bsxfun(@eq,H,S'))

Upvotes: 4

Floris
Floris

Reputation: 46365

How about 

result = sum(H==repmat(S(:),[1 size(H,2)]))==4;

Upvotes: 2

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