title: Remove a duplicate point from polygon in Shapely
body: <p>To remove duplicate lists from a list, there are several nice ways in Python - <a href="https://stackoverflow.com/a/12198497/2327328">for example</a>:</p>
  
  <pre><code>a = [[ 9.1514622, 47.1166004 ], [ 9.1513045, 47.1164599 ], [ 9.1516278, 47.1163001 ], [ 9.1517832, 47.1164408 ], [ 9.1514622, 47.1166004 ] ] 
  
  print len(a) # 5
  b_set = set(map(tuple,a))
  b = map(list,b_set)
  print len(b) # 4
  </code></pre>
  
  <p>But unfortunately, I had to convert my list to a <a href="http://shapely.readthedocs.io/en/stable/manual.html#polygons" rel="nofollow noreferrer">Shapely Polygon</a> object, in which I need to simplify the geometry and do some other geo functions. </p>
  
  <pre><code>from shapely.geometry import Polygon
  a = [[[ 9.1514622, 47.1166004 ], [ 9.1513045, 47.1164599 ], [ 9.1516278, 47.1163001 ], [ 9.1517832, 47.1164408 ], [ 9.1514622, 47.1166004 ] ] ]
  polys = [Polygon(item) for item in a] # convert list to polygon
  print len(polys) # prints 5
  </code></pre>
  
  <p><a href="https://stackoverflow.com/q/31622618/2327328">This answer</a> shows how to remove a duplicate Polygon from a list of Polygons, but how can I remove a duplicate point from a list of points, as a Shapely polygon?</p>
  
  <p>I guess it's possible to convert it back to a list, remove duplicates, and then re-convert to Polygon. </p>
  
  <p>But that seems overly complicated. Any ideas on how to do this?</p>