'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 :) ?

[Walter Roberson]

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

Also, should the new matrix have fewer columns?

[TAB]

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

[Jan]

@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.

[Hello kity]

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

[Jan]

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

[Walter Roberson]

Have you considered circshift() up by 4 rows?

Answer 2

[Azzi Abdelmalek]

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

[Hello kity]

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

thank you

[Azzi Abdelmalek]

 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

[Andrei Bobrov]

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]));

[Hello kity]

thank you,

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

Answer 4

[Jan]

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)];