intersect(A,B) returns the data with no repetitions

Dear Sir/Madam,

I was using "intersect" in my Matlab code where I want the following:

A = [ 4 1 1 2 3];

[B] = sort(A, 'ascend'); % so that B is sorting A in ascending order, so I got B = [1 1 2 3 4]

[same,a] = intersect(B,A);

I want same = [1 1 2 3 4] but the simulation gives me same = [1 2 3 4] by omitting the repeated '1'.

I understand by using intersect it will return data with no repetition

 C = intersect(A,B) returns the data common to both A and B with no repetitions.

I want it to show the complete data including those repetition, what are the alternatives I can use rather than the function "intersect"?

For example:

A = [ 4 1 1 2 3];

[B] = sort(A, 'ascend'); % so that B is sorting A in ascending order, so I got B = [1 1 2 3 4]

[same,a] = intersect(B,A);

So now I want it to be like this same =[1 1 2 3 4] and a=[2 3 4 5 1].

I need to access ‘a’ where ‘a’ shows the original index prior to sorting so I can use it for further processing.

Thank you very much.

Answer 1

[Jos (10584)]

I think you are looking for the second output of SORT

A = [ 4 1 1 2 3]
[B, ix] = sort(A, 'ascend')

Now, B equals A(ix)

[want2know]

Thanks a lot, it is working now, you are absolutely right, sorry for making such silly mistake.

Answer 2

[Laurent]

You can use the function 'ismember' for this purpose.

From the help:

    LIA = ismember(A,B) for arrays A and B returns an array of the same
    size as A containing true where the elements of A are in B and false 
    otherwise.

[want2know]

Dear Laurent,

Thanks so much for your reply. Sorry that I should have made it clearer: The below shows details:

A = [ 4 1 1 2 3];

[B] = sort(A, 'ascend'); % so that B is sorting A in ascending order, so I got B = [1 1 2 3 4]

[same,a] = intersect(B,A);

So now I want it to be like this same =[1 1 2 3 4] and a=[2 3 4 5 1].

I need to access ‘a’ where ‘a’ shows the original index prior to sorting so I can use it for further processing.

I hope I make myself clear this time, thank you very much.

Answer 3

[Jos (10584)]

I do not get it. Will same not always be exactly B?

[want2know]

Sorry Jos, I should have made it clearer, please refer to my edited question, thanks for your time