title: How to find most similar lines on seperate charts
body: <p>I have just printed my four PHP arrays into charts and get something like this:
  <a href="https://i.stack.imgur.com/eJY4w.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eJY4w.png" alt="enter image description here" /></a></p>
  <p>I am looking for a way, how can I find these arrays(charts) on which the red line is the most similar to the blue line. So in this case I am looking for charts with numbers <code>1.</code>, <code>2.</code> and <code>4.</code> In chart <code>3.</code> the values are completely random, so I am not interested in that chart.</p>
  <p>I have tried to divide values from the red line by values from the blue line, but it does not work.
  I have also tried to subtract values from the red line from values from the blue line, but it also does not work.</p>
  <p>How can I find the charts, where the blue and red line is in very similar shape?</p>