title: Use customized markers in FastMarkerCluster in Python folium?
body: <p>I'm able to add data to a folium map using MarkerCluster and vary the parameters of the marker according to parameters for each point.</p>
  
  <pre><code>###Toy Example 1###
  
  
  import pandas as pd
  import numpy as np
  import folium
  import folium.plugins as plugins
  
  lats = np.asarray([-54.4, -54.5, -54.6])
  longs = np.asarray([-69.5, -69.5, -69.5])
  data = np.asarray([70, 90, 5])
  colour = np.asarray(['green', 'orange', 'red'])
  
  dummy = [list(a) for a in zip(lats, longs, data, colour)]
  
  dummy2 = pd.DataFrame(dummy, columns=['lat', 'lng', 'data', 'colour'])
  
  dmap = folium.Map(location = [-54.5, -69.5], zoom_start = 7)
  
  mc=plugins.MarkerCluster()
  
  for a, row in dummy2.iterrows():
      folium.CircleMarker(location=[row[0],row[1]],
                          radius=row[2], color=row[3], fill=True).add_to(mc)
  
  mc.add_to(dmap)
  
  dmap
  </code></pre>
  
  <p>As my use case has thousands of points, I would like to do something similar to the above with FastMarkerCluster.  The farthest I've gone to achieving this is is:</p>
  
  <pre><code>###Toy Example 2###
  
  callback = """\
  function (row) {
      var marker;
      marker = L.circle(new L.LatLng(row[0], row[1]), {color:'red'});
      return marker;
  };
  """
  
  lats = np.asarray([-54.4, -54.5, -54.6])
  longs = np.asarray([-69.5, -69.5, -69.5])
  data = np.asarray([70, 90, 5])
  colour = np.asarray(['green', 'orange', 'red'])
  
  dummy = [list(a) for a in zip(lats, longs)]
  
  dummy2 = pd.DataFrame(dummy, columns=['lat', 'lng'])
  
  dmap = folium.Map(location = [-54.5, -69.5], zoom_start = 7)
  
  plugins.FastMarkerCluster(dummy, callback=callback).add_to(dmap)
  
  dmap
  </code></pre>
  
  <p>I can envision adding <code>{radius: row[2], color: row[3]}</code> to the callback to get the functionality I want.  However, if I add the <code>data</code> and/or <code>colour</code> arrays to <code>dummy</code> (as in Toy Example 1), I get <code>TypeError: must be real number, not numpy.str_</code>.  If I use <code>dummy2</code> in Toy Example 2, I get <code>TypeError: must be real number, not str</code>.</p>
  
  <p>Any help on this is greatly appreciated.
  f
  Cheers,
  -R</p>