title: Tkinter create_line problem: wrong # coordinates: expected an even number
body: <p>here goes my first ever question, im doing a basic logplayer from data in a txt file:</p>
  
  <p>the code is something like:</p>
  
  <pre><code>    for aircraft in self.logArray.itervalues():
  
          for logLine in aircraft:
              currentPoint = self.point(logLine[1], logLine[2])
              currentPoint = self.win2canvas(currentPoint)
              points = np.append(points, currentPoint)
  
          print points
          print np.size(points)
          self.canvas.create_line(points)
          points = np.array([])
  </code></pre>
  
  <p>So  logArray is a dictionary, each name contains an array of kind [time,x,y], so there will be an array like that for each aircraft name.</p>
  
  <p>The second for simply converts to tkinter canvas coords and appends the currentPoint to the pre-existing (and initialized).</p>
  
  <p>When it gets to the create_line method, i get:</p>
  
  <pre><code>File "/home/joao/tese/workspace/ATC/src/autoATC/LogPlayer.py", line 131, in drawPath
  self.canvas.create_line(points)
    File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2204, in create_line
  return self._create('line', args, kw)
    File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2192, in _create
  *(args + self._options(cnf, kw))))
  _tkinter.TclError: wrong # coordinates: expected an even number, got 399
  </code></pre>
  
  <p>I've manually checked the size of the points array and is indeed even numbered. So i double-checked using  np.size, which returned 398!</p>
  
  <p>I've also tried using a very similar test approach, doing:</p>
  
  <pre><code>    self.canvas.create_line([123,345,234,453,23,34,45,56,67,78]) 
  </code></pre>
  
  <p>which went perfectly!  I don't get why, but somehow my points array ends up getting an extra element, and I don't know where from!</p>
  
  <p>Thank you for your time and patience!</p>