title: Python: method to remove all duplicate points from a X,Y,Z file that have identical x and y coordinates
body: <p>I am looking a method to removes all duplicate points from a a X,Y,Z file. What i wish to code is remove points that have identical x and y coordinates. The first point survives, all subsequent duplicates are removed.</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  import matplotlib.mlab as ml
  import matplotlib.delaunay
  from matplotlib.mlab import griddata
  
  # my area boundary box
  xmax, xmin, ymax, ymin = 640000.06, 636999.83, 6070000.3, 6066999.86
  
  # generate fake data
  ndata = 500000
  # Generate random data to simulate
  x = np.random.randint(xmin, xmax, ndata)
  y = np.random.randint(ymin, ymax, ndata)
  z = np.random.randint(0,20,ndata)
  mypoints = zip(x,y,z)
  </code></pre>
  
  <p>Thanks in advance for helps and tips!!!
  :)</p>