Repeat rows that start with a particular value

Hi, I am trying to repeat a column in an array where all columns start with 1. Example, I want row 2 (1110100) to be repeated in rows where the second column contain 1. So this would apply to the first and last row.

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

which I want to look like this

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

Answer 1

[Image Analyst]

Try this to find the rows that need repeating:

m = [...
  0     1     0     0     0     0     0
  1     1     1     0     1     0     0
  0     0     0     0     0     0     0
  0     0     0     0     0     0     0
  0     1     0     0     0     0     0]
rowsToRepeat = m(:, 2) == 1

We can't fully answer the question because you did not say where you want the repeated rows to go. Do you want to append them to the end? Do you want the repeated row to go right below it's original location?

[Andre Munoz]

Thanks for the reply. Please see that I have updated the original question for you to answer.

[Image Analyst]

You should learn about repmat(). Here's one way:

m = [...
  0     1     0     0     0     0     0
  1     1     1     0     1     0     0
  0     0     0     0     0     0     0
  0     0     0     0     0     0     0
  0     1     0     0     0     0     0]
[rows, columns] = size(m);
rowsToRepeat = m(:, 2) == 1
allRow2 = repmat(m(2,:), [rows, 1])
m(rowsToRepeat, :) = allRow2(rowsToRepeat,:)

Here is another way:

rowsToRepeat = m(:, 2) == 1
m(rowsToRepeat, :) = repmat(m(2,:), [sum(rowsToRepeat), 1])

[Andre Munoz]

This has worked. Thank you very much.

[Andre Munoz]

Please can you help me again. Now I want to take the top row (0100000) and repeat this where there are zeros in the first column. I have tried my self but this does not work for me. Thanks

[Andre Munoz]

Don't worry, I now have it working thanks.