Replacing each array element with a series of values

Hi, I have a a 1 x N matrix of numbers. For example, a matrix T:

T = [1 4 7]

I would like to convert T to the new matrix as follows:

T_new = [1 2 3 4 5 6 7 8 9]

Basically, each element of T is replaced by an arithmetic series of 3 values with that element as the starting element and common difference = 1.

I tried

T_new = [T:T+3];

But it only updates the first element (I get T_new = [1 2 3 4]). Is there any quick way to do this without using a for loop ?

Thanks.

Answer 1

[Stephen23]

>> T = [1,4,7];
>> cell2mat(arrayfun(@(n)n+(0:2),T,'uni',0))
ans =
   1   2   3   4   5   6   7   8   9

Answer 2

[Andrei Bobrov]

T_new = reshape(T(:)' + (0:2)',1,[])

[Varun Nair]

There is an error in the above code. But I get the idea. The below code works:

    reshape(repmat(T,numel(T),1) + repmat((0:2)',1,numel(T)),1,[])

[Andrei Bobrov]

You are using an older version of MATLAB.

Variant for you:

T_new = reshape(bsxfun(@plus,T(:)',(0:2)'),1,[])

[Varun Nair]

Yup, this works. Thanks !

Answer 3

[dbmn]

One possible solution would be:

0. having

T = [1 4 7];

1. create a temporary matrix T_temp that looks like (this could be done in a loop very easily)

T_new = [1 2 3;
         4 5 6;
         7 8 9 ];

2. then reshape that matrix using

T_new=reshape(T_tmp', 1, numel(T_tmp));
1 2 3 4 5 6 7 8 9

[Varun Nair]

Thanks, but, as I mentioned in the question, I was looking for a way to do it without using a for loop (i.e. without having to loop through all elements).