Issues with Folium Choropleth Mapping Example

Question

I am trying to create a choropleth map using folium, following the example here: https://pypi.python.org/pypi/folium. The goal is to produce a choropleth map of US unemployment rates, but when I open my map US states are not shaded in. Any suggestions?

import folium
import pandas as pd

state_geo = r'data/us-states.json'
state_unemployment = r'data/US_Unemployment_Oct2012.csv'

state_data = pd.read_csv(state_unemployment)

#Let Folium determine the scale
map = folium.Map(location=[48, -102], zoom_start=3)
map.geo_json(geo_path=state_geo, data=state_data,
             columns=['State', 'Unemployment'],
             key_on='feature.id',
             fill_color='YlGn', fill_opacity=0.7, line_opacity=0.2,
             legend_name='Unemployment Rate (%)')
map.create_map(path='us_states.html')

Thanks,

Answer 1

I think the issue is a mis-match of column names:

1) data=state_data has columns ['State', 'Unemployment'] 2) if you open us-states.json, you will find key_on='feature.id' corresponds to '01', '02' and so on..

In folium key_on is suppose to match the first column of data, in this case 'State'.

But '01', '02' ..doesn't fit 'State' column which has 'AL', 'AK', 'AZ'..

If you could come up with key_on in us-states.json that matches 'States' columns, I think it should solve your problem.

Note: I am assuming us-states.json is from https://raw.githubusercontent.com/alignedleft/d3-book/master/chapter_12/us-states.json and US_Unemployment_Oct2012.csv from https://raw.githubusercontent.com/python-visualization/folium/master/examples/US_Unemployment_Oct2012.csv