matlab - creating a single dimensional array from two dimensional parts

Question

hi i have the following situation

      h = [0,1,1,1;
           0,0,0,0;
           1,1,1,1];

i'll check incoming values which can range between 0 and rowsize of h, i.e. in this case 2,. so my options are 0,1,2.

now i want to create a single dimensional array (let's name it j) as follows

whenever the incoming value is 0

j = [0,1,1,1]

next time if the incoming value is 1

then j = [0,1,1,1,0,0,0,0]

and so on... how is it possible to achieve this in matlab? thanks!

Answer 1

If the incoming value is x, you could do something like:

g = h.'
j = g(1:(x+1)*size(h,2))

Answer 2

Hi

Matlab, as you know, indexes from 1 so you will need to add 1 to the index 0,1,2 to get the row identifier for h. So if the input is 'index'

j = h(index+1,:)

Then, for the next index

j = [j h(index+1,:)]

and so on.

Regards

Mark

Answer 3

Try this (with x as your vector of incoming values):

j = reshape(h(x+1,:).',1,[]);

The above uses x+1 as an index to select copies of the rows, then transposes and reshapes the result into a single row vector. Here's a test:

>> h = [0 1 1 1; 0 0 0 0; 1 1 1 1];
>> x = [0 0 0];
>> j = reshape(h(x+1,:).',1,[])

j =

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