title: Create random sequence of comparison pairs (x, y) so that subsequent x and y values are not repeated
body: <p>I have the following list:</p>
  <pre><code>item_list = [1, 2, 3, 4, 5]
  </code></pre>
  <p>I want to compare each item in the list to the other items to generate comparison pairs, such that the same comparisons (x, y) and (y, x) are not repeated (i.e. I don't want both [1, 5] and [5, 1]). For the 5 items in the list, this would generate a total of 10 comparison pairs (n*(n-1)/2). I also want to randomize the order of the pairs such that both x- and y-values aren't the same as the adjacent x- and y-values.</p>
  <p>For example, this is fine:</p>
  <pre><code>[1, 5]
  [3, 2]
  [5, 4]
  [4, 2]
  ...
  </code></pre>
  <p>But not this:</p>
  <pre><code>[1, 5]
  [1, 4] &lt;-- here the x-value is the same as the previous x-value
  [2, 4] &lt;-- here the y-value is the same as the previous y-value
  [5, 3]
  ...
  </code></pre>
  <p>I have only been able to come up with a method in which I manually create the pairs by zipping two lists together (example below), but this is obviously very time-consuming (and would be even more so if I wanted to increase the list of items to 10, which would generate 45 pairs). I also can't randomize the order each time, otherwise I could get repetitions of the same x- or y-values.</p>
  <pre><code>x_list = [1, 4, 1, 3, 1, 4, 1, 2, 5, 3] 
  y_list = [2, 5, 3, 5, 4, 2, 5, 3, 2, 4] 
  zip_list = zip(x_list, y_list)
  paired_list = list(zip_list) 
  print(paired_list)
  </code></pre>
  <p>I hope that makes sense. I am very new to coding, so any help would be much appreciated!</p>
  <p>Edit: For context, my experiment involves displaying two images next to each other on the screen. I have a total of 5 images (labeled 1-5), hence the 5-item list. For each image pair, the participant must select one of the two images, which is why I don't want the same image displayed at the same time (e.g. [1, 1]), and I don't need the same pair repeated (e.g. [1, 5] and [5, 1]). I also want to make sure that each time the screen displays a new pair of images, both images, in their respective positions on the screen, change. So it doesn't matter if an image repeats in the sequence, so as long as it changes position (e.g. [4, 3] followed by [5, 4] is ok).</p>