title: How to get relative paths with Pathlib
body: <p>I started using <code>from pathlib import Path</code> in place of <code>os.path.join()</code> to concatenate my paths. Taking the following code into consideration:</p>
  
  <pre><code>from pathlib import Path
  import cv2
  
  rootfolder = "rootyrooty"
  file = "alittlefile"
  image_path = Path(rootfolder, file)
  image = cv2.imread(image_path.as_posix())
  </code></pre>
  
  <p>I'm using <code>image_path.as_posix()</code> to get a full string so I can pass <code>image_path</code> into <code>imread</code> function. Directly typing <code>image_path</code> doesn't works since it returns <code>WindowsPath('rootyrooty/alittlefile')</code> but I need <code>"rootyrooty/alittlefile"</code> (Since <code>imread</code> accepts strings instead of windowsPath objects). Do I have to use another component from <code>pathlib</code> instead of <code>Path</code> so I can just feed <code>image_path</code> into <code>imread</code> function. Like:</p>
  
  <pre><code>from pathlib import thefunctionyetidontknow
  image_path = thefunctionyetidontknow("rootyrooty","alittlefile")
  print("image_path")
  # returns "rootyrooty/alittlefile"
  </code></pre>
  
  <p>Thanks.</p>