title: Choropleth map doesn't colour according to variables values (Python)
body: <p>I'm trying to make a simple Choropleth map in Python using Folium. The geometry of the data seems to be visiable, however polygons are not coloured according to field values. I feel that the problem is in how I define <code>key_on</code>. The solution must be simple but I can't really figure out what is the problem. Any advices?</p>
  <p>The code:</p>
  <pre><code>import folium
  
  import geopandas as gpd
  
  import pandas as pd
  
  gj = gpd.read_file(&quot;C:/landuse_comparative.geojson&quot;)
  
  gj = gj[['osm_id','area','geometry']]
  
  gj_map = folium.Map(location=['53.212680', '50.187837'], zoom_start=11,tiles=None)
  
  folium.TileLayer('CartoDB positron',name=&quot;Light Map&quot;,control=False).add_to(gj_map)
  
  gj_map.choropleth(geo_data=gj,      
               data=gj,
               columns=['osm_id','area'], 
               key_on='feature.properties.area', 
               fill_color='YlOrRd',
               fill_opacity=0.6, 
               line_opacity=0.8,
               legend_name='Area', 
               smooth_factor=0,     
               highlight=True
                   )
  
  gj_map.save(&quot;C:/map.html&quot;)
  </code></pre>
  <p>The geojson:
  <a href="https://drive.google.com/drive/u/0/folders/1lgRnunVXxOI5daLElbVa4ef8HBkxF6uS" rel="nofollow noreferrer">https://drive.google.com/drive/u/0/folders/1lgRnunVXxOI5daLElbVa4ef8HBkxF6uS</a></p>