title: Streamlines for irregular spaced wind data in R?
body: <p>I have got wind data for some stations. The data includes station latitude, longitude, wind speed and wind direction for each station in a csv file. This data is not regularly spaced data. I have a requirement to draw streamlines for this data in R language. </p>
  
  <p>I tried couple of packages <code>rasterVis</code> for <code>STREAMPLOT()</code>, <code>TeachingDemos</code> for <code>My.Symbols</code> by searching through internet, however I was not successful. </p>
  
  <p>Here is an example plot I was talking about. 
  <a href="http://wx.gmu.edu/dev/clim301/850stream.png" rel="nofollow noreferrer">http://wx.gmu.edu/dev/clim301/850stream.png</a></p>
  
  <p>Also here is some sample data from csv file that I got for which I was trying to draw streamlines.</p>
  
  <pre><code>longitude,latitude,windspeed,winddirection  
  84.01,20,1.843478261,126.6521739  
  77.13,28.48,3.752380952,138.952381  
  77.2,28.68,2.413333333,140.2666667  
  78.16,31.32,1.994444444,185.0555556  
  77.112,31.531,2.492,149.96  
  77,28.11,7.6,103  
  77.09,31.5,1.752631579,214.8947368  
  76.57,31.43,1.28,193.6  
  77.02,32.34,3.881818182,264.4545455  
  77.15,28.7,2.444,146.12  
  77.35,30.55,3.663157895,131.3684211  
  75.5,29.52,4.175,169.75  
  72.43,24.17,2.095,279.3  
  76.19,25.1,1.816666667,170  
  76.517,30.975,1.284210526,125.6315789  
  76.13,28.8,4.995,126.7  
  75.04,29.54,4.09,151.85  
  72.3,24.32,0,359  
  72.13,23.86,1.961111111,284.7777778  
  74.95,30.19,3.032,137.32  
  73.16,22.36,1.37,251.8  
  75.84,30.78,3.604347826,125.8695652  
  73.52,21.86,1.816666667,228.9166667  
  70.44,21.5,2.076,274.08  
  69.75,21.36,3.81875,230  
  78.05,30.32,0.85625,138.5625  
  </code></pre>
  
  <p>Can someone please help me out in drawing streamlines for the irregular wind data?</p>