title: Extracting the value of 2-d gridded field by scatter points in Python
body: <p>I have a 2-d gridded files which represents the land use catalogues for the place of interest.<br>
  I also have some lat/lon based point distributed in this area. </p>
  
  <pre><code>from netCDF4 import Dataset
  
  ## 2-d gridded files
  nc_file = "./geo_em.d02.nc"
  geo = Dataset(nc_file, 'r')
  lu = geo.variables["LU_INDEX"][0,:,:]
  lat = geo.variables["XLAT_M"][0,:]  
  lon = geo.variables["XLONG_M"][0,:] 
  
  ## point files
  point = pd.read_csv("./point_data.csv")
  plt.pcolormesh(lon,lat,lu)
  plt.scatter(point_data.lon,cf_fire_data.lat, color ='r')   
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/PQWyD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PQWyD.png" alt="enter image description here"></a></p>
  
  <p>I want to extract the values of the 2-d gridded field which those points belong, but I found it is difficult to define a simple function to solve that.  </p>
  
  <p>Is there any efficient method to achieve it?  </p>
  
  <p>Any advices would be appreciated.</p>
  
  <h2>PS</h2>
  
  <p>I have uploaded my files here</p>
  
  <p><a href="https://drive.google.com/open?id=1FExIttr8RxVJG_Pjqa928Oa1RIvrdoUz" rel="nofollow noreferrer">1. nc_file</a><br>
  <a href="https://drive.google.com/open?id=1xOcH8i1CjNmUpaILQ-R6wzUaguJPsk9l" rel="nofollow noreferrer">2. point_file</a></p>