'How to' Matrix

I have an array with 0 s and 1s.

Example a colomn, 0 ,0 ,0 ,0 , 1.

Now the 1 is on the 5th row, I want to raise that to the first row.

So, in my code i want all the ones to go 4 steps up...

sounds easy, but how :) ?

What if there is a 1 in the first 4 columns?

Also, should the new matrix have fewer columns?

Then what should be left in 5th column (or row in your words) ?

@Student: The question remains, what "raise to the first row" exactly means. At first I guess it is the "first column", but "raising" can be swapping, shifting, circular shifting, sorting, cropping or any procedure I cannot imagine currently.

I meant shifting, shifting the 1 on the 4th row to the 1st.

Thanks for the clarification, Student. And what happens on the right margin? Is the result shorter, filled with zeros or ones or with the value of the last element?

Answer 1

Have you considered circshift() up by 4 rows?

Answer 2

A=[0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1]
for k=5:length(A)
   if A(k)
       b=A(k-4:k-1);
       A(k-4)=1
       A(k-4+1:k)=b
   end
end

Would you comment this code step by step, I dont get how you do this...

thank you

 A=[0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1]
for k=5:length(A)
   if A(k)            % If A(k) is equal to 1
       b=A(k-4:k-1);  % store value from k-4 to k-1 in b
       A(k-4)=1       % replace value at k-1 by 1
       A(k-4+1:k)=b   % shift value stored in b 
   end
end

Answer 3

other way:

a - your vector - row (eg: [0 0 0 0 1])

n = numel(a);
out = a(hankel(1:n,[n,1:n-1]));

or

out = hankel(a,circshift(a,[0 1]));

thank you,

afterwards i use Q=out(:,5);

Answer 4

Some ideas:

x = [0, 0, 0, 0, 1];
index = find(x, 1, 'first');
y1 = x(index:end);
y2 = [x(index:end), zeros(1, index - 1)];
y3 = [x(index:end), ones(1, index - 1)];
y4 = [x(index:end), repmat(x(end), 1, index - 1)];
y5 = [x(index:end), x(1:index - 1)];